diff --git a/docs/en/3_exist_data_new_model.md b/docs/en/3_exist_data_new_model.md
index c69afd20386..7201ffdecb6 100644
--- a/docs/en/3_exist_data_new_model.md
+++ b/docs/en/3_exist_data_new_model.md
@@ -41,6 +41,12 @@ mmdetection
 
 ```
 
+Or you can set your dataset root through
+```bash
+export MMDET_DATASETS=$data_root
+```
+We will replace dataset root with `$MMDET_DATASETS`, so you don't have to modify the corresponding path in config files.
+
 The cityscapes annotations have to be converted into the coco format using `tools/dataset_converters/cityscapes.py`:
 
 ```shell
diff --git a/docs/zh_cn/3_exist_data_new_model.md b/docs/zh_cn/3_exist_data_new_model.md
index 5ac09c01afb..a9c19ca9428 100644
--- a/docs/zh_cn/3_exist_data_new_model.md
+++ b/docs/zh_cn/3_exist_data_new_model.md
@@ -40,6 +40,13 @@ mmdetection
 │   │   ├── VOC2012
 ```
 
+你也可以通过如下方式设定数据集根路径
+```bash
+export MMDET_DATASETS=$data_root
+```
+我们将会使用环境便变量 `$MMDET_DATASETS` 作为数据集的根目录，因此你无需再修改相应配置文件的路径信息。
+
+
 你需要使用脚本 `tools/dataset_converters/cityscapes.py` 将 cityscapes 标注转化为 coco 标注格式。
 
 ```shell
diff --git a/mmdet/utils/__init__.py b/mmdet/utils/__init__.py
index 3873ec09c67..a6635d3c0f2 100644
--- a/mmdet/utils/__init__.py
+++ b/mmdet/utils/__init__.py
@@ -1,10 +1,11 @@
 # Copyright (c) OpenMMLab. All rights reserved.
 from .collect_env import collect_env
 from .logger import get_caller_name, get_root_logger, log_img_scale
-from .misc import find_latest_checkpoint
+from .misc import find_latest_checkpoint, update_data_root
 from .setup_env import setup_multi_processes
 
 __all__ = [
     'get_root_logger', 'collect_env', 'find_latest_checkpoint',
-    'setup_multi_processes', 'get_caller_name', 'log_img_scale'
+    'update_data_root', 'setup_multi_processes', 'get_caller_name',
+    'log_img_scale'
 ]
diff --git a/mmdet/utils/misc.py b/mmdet/utils/misc.py
index f5c425300e4..4113672acfb 100644
--- a/mmdet/utils/misc.py
+++ b/mmdet/utils/misc.py
@@ -1,8 +1,12 @@
 # Copyright (c) OpenMMLab. All rights reserved.
 import glob
+import os
 import os.path as osp
 import warnings
 
+import mmcv
+from mmcv.utils import print_log
+
 
 def find_latest_checkpoint(path, suffix='pth'):
     """Find the latest checkpoint from the working directory.
@@ -36,3 +40,37 @@ def find_latest_checkpoint(path, suffix='pth'):
             latest = count
             latest_path = checkpoint
     return latest_path
+
+
+def update_data_root(cfg, logger=None):
+    """Update data root according to env MMDET_DATASETS.
+
+    If set env MMDET_DATASETS, update cfg.data_root according to
+    MMDET_DATASETS. Otherwise, using cfg.data_root as default.
+
+    Args:
+        cfg (mmcv.Config): The model config need to modify
+        logger (logging.Logger | str | None): the way to print msg
+    """
+    assert isinstance(cfg, mmcv.Config), \
+        f'cfg got wrong type: {type(cfg)}, expected mmcv.Config'
+
+    if 'MMDET_DATASETS' in os.environ:
+        dst_root = os.environ['MMDET_DATASETS']
+        print_log(f'MMDET_DATASETS has been set to be {dst_root}.'
+                  f'Using {dst_root} as data root.')
+    else:
+        return
+
+    assert isinstance(cfg, mmcv.Config), \
+        f'cfg got wrong type: {type(cfg)}, expected mmcv.Config'
+
+    def update(cfg, src_str, dst_str):
+        for k, v in cfg.items():
+            if isinstance(v, mmcv.ConfigDict):
+                update(cfg[k], src_str, dst_str)
+            if isinstance(v, str) and src_str in v:
+                cfg[k] = v.replace(src_str, dst_str)
+
+    update(cfg.data, cfg.data_root, dst_root)
+    cfg.data_root = dst_root
diff --git a/tools/analysis_tools/analyze_results.py b/tools/analysis_tools/analyze_results.py
index cb79587a65c..15db07e41c7 100644
--- a/tools/analysis_tools/analyze_results.py
+++ b/tools/analysis_tools/analyze_results.py
@@ -9,6 +9,7 @@
 from mmdet.core.evaluation import eval_map
 from mmdet.core.visualization import imshow_gt_det_bboxes
 from mmdet.datasets import build_dataset, get_loading_pipeline
+from mmdet.utils import update_data_root
 
 
 def bbox_map_eval(det_result, annotation):
@@ -186,6 +187,10 @@ def main():
     mmcv.check_file_exist(args.prediction_path)
 
     cfg = Config.fromfile(args.config)
+
+    # update data root according to MMDET_DATASETS
+    update_data_root(cfg)
+
     if args.cfg_options is not None:
         cfg.merge_from_dict(args.cfg_options)
     cfg.data.test.test_mode = True
diff --git a/tools/analysis_tools/benchmark.py b/tools/analysis_tools/benchmark.py
index 91f34c74063..2be2d14d7b4 100644
--- a/tools/analysis_tools/benchmark.py
+++ b/tools/analysis_tools/benchmark.py
@@ -13,6 +13,7 @@
 from mmdet.datasets import (build_dataloader, build_dataset,
                             replace_ImageToTensor)
 from mmdet.models import build_detector
+from mmdet.utils import update_data_root
 
 
 def parse_args():
@@ -170,6 +171,10 @@ def main():
     args = parse_args()
 
     cfg = Config.fromfile(args.config)
+
+    # update data root according to MMDET_DATASETS
+    update_data_root(cfg)
+
     if args.cfg_options is not None:
         cfg.merge_from_dict(args.cfg_options)
 
diff --git a/tools/analysis_tools/confusion_matrix.py b/tools/analysis_tools/confusion_matrix.py
index a2531ba81f9..224b93b314a 100644
--- a/tools/analysis_tools/confusion_matrix.py
+++ b/tools/analysis_tools/confusion_matrix.py
@@ -10,6 +10,7 @@
 
 from mmdet.core.evaluation.bbox_overlaps import bbox_overlaps
 from mmdet.datasets import build_dataset
+from mmdet.utils import update_data_root
 
 
 def parse_args():
@@ -230,6 +231,10 @@ def main():
     args = parse_args()
 
     cfg = Config.fromfile(args.config)
+
+    # update data root according to MMDET_DATASETS
+    update_data_root(cfg)
+
     if args.cfg_options is not None:
         cfg.merge_from_dict(args.cfg_options)
 
diff --git a/tools/analysis_tools/eval_metric.py b/tools/analysis_tools/eval_metric.py
index 1fcdc1c1fa9..a074c9e1850 100644
--- a/tools/analysis_tools/eval_metric.py
+++ b/tools/analysis_tools/eval_metric.py
@@ -5,6 +5,7 @@
 from mmcv import Config, DictAction
 
 from mmdet.datasets import build_dataset
+from mmdet.utils import update_data_root
 
 
 def parse_args():
@@ -48,6 +49,10 @@ def main():
     args = parse_args()
 
     cfg = Config.fromfile(args.config)
+
+    # update data root according to MMDET_DATASETS
+    update_data_root(cfg)
+
     assert args.eval or args.format_only, (
         'Please specify at least one operation (eval/format the results) with '
         'the argument "--eval", "--format-only"')
diff --git a/tools/analysis_tools/optimize_anchors.py b/tools/analysis_tools/optimize_anchors.py
index d0da0cbc61d..acf72acb26c 100644
--- a/tools/analysis_tools/optimize_anchors.py
+++ b/tools/analysis_tools/optimize_anchors.py
@@ -29,7 +29,7 @@
 
 from mmdet.core import bbox_cxcywh_to_xyxy, bbox_overlaps, bbox_xyxy_to_cxcywh
 from mmdet.datasets import build_dataset
-from mmdet.utils import get_root_logger
+from mmdet.utils import get_root_logger, update_data_root
 
 
 def parse_args():
@@ -325,6 +325,9 @@ def main():
     cfg = args.config
     cfg = Config.fromfile(cfg)
 
+    # update data root according to MMDET_DATASETS
+    update_data_root(cfg)
+
     input_shape = args.input_shape
     assert len(input_shape) == 2
 
diff --git a/tools/misc/browse_dataset.py b/tools/misc/browse_dataset.py
index 3e70c8b8741..14db64ee050 100644
--- a/tools/misc/browse_dataset.py
+++ b/tools/misc/browse_dataset.py
@@ -11,6 +11,7 @@
 from mmdet.core.utils import mask2ndarray
 from mmdet.core.visualization import imshow_det_bboxes
 from mmdet.datasets.builder import build_dataset
+from mmdet.utils import update_data_root
 
 
 def parse_args():
@@ -55,6 +56,10 @@ def skip_pipeline_steps(config):
         ]
 
     cfg = Config.fromfile(config_path)
+
+    # update data root according to MMDET_DATASETS
+    update_data_root(cfg)
+
     if cfg_options is not None:
         cfg.merge_from_dict(cfg_options)
     train_data_cfg = cfg.data.train
diff --git a/tools/misc/print_config.py b/tools/misc/print_config.py
index 1b2cb30c24c..7bb20fa60de 100644
--- a/tools/misc/print_config.py
+++ b/tools/misc/print_config.py
@@ -4,6 +4,8 @@
 
 from mmcv import Config, DictAction
 
+from mmdet.utils import update_data_root
+
 
 def parse_args():
     parser = argparse.ArgumentParser(description='Print the whole config')
@@ -42,6 +44,10 @@ def main():
     args = parse_args()
 
     cfg = Config.fromfile(args.config)
+
+    # update data root according to MMDET_DATASETS
+    update_data_root(cfg)
+
     if args.cfg_options is not None:
         cfg.merge_from_dict(args.cfg_options)
     print(f'Config:\n{cfg.pretty_text}')
diff --git a/tools/test.py b/tools/test.py
index dfbc425869e..baa149d8418 100644
--- a/tools/test.py
+++ b/tools/test.py
@@ -17,7 +17,7 @@
 from mmdet.datasets import (build_dataloader, build_dataset,
                             replace_ImageToTensor)
 from mmdet.models import build_detector
-from mmdet.utils import setup_multi_processes
+from mmdet.utils import setup_multi_processes, update_data_root
 
 
 def parse_args():
@@ -133,6 +133,10 @@ def main():
         raise ValueError('The output file must be a pkl file.')
 
     cfg = Config.fromfile(args.config)
+
+    # update data root according to MMDET_DATASETS
+    update_data_root(cfg)
+
     if args.cfg_options is not None:
         cfg.merge_from_dict(args.cfg_options)
 
diff --git a/tools/train.py b/tools/train.py
index 2ccc1c88f84..5f184608f1c 100644
--- a/tools/train.py
+++ b/tools/train.py
@@ -17,7 +17,8 @@
 from mmdet.apis import init_random_seed, set_random_seed, train_detector
 from mmdet.datasets import build_dataset
 from mmdet.models import build_detector
-from mmdet.utils import collect_env, get_root_logger, setup_multi_processes
+from mmdet.utils import (collect_env, get_root_logger, setup_multi_processes,
+                         update_data_root)
 
 
 def parse_args():
@@ -103,6 +104,10 @@ def main():
     args = parse_args()
 
     cfg = Config.fromfile(args.config)
+
+    # update data root according to MMDET_DATASETS
+    update_data_root(cfg)
+
     if args.cfg_options is not None:
         cfg.merge_from_dict(args.cfg_options)