diff --git a/mmseg/core/__init__.py b/mmseg/core/__init__.py
index 0f2fcf13c1a2cf30a48412d9efaabbbe7b227e40..39fa62423356dd6d351f5f3e38372cf989ebae74 100644
--- a/mmseg/core/__init__.py
+++ b/mmseg/core/__init__.py
@@ -1,5 +1,6 @@
# Copyright (c) OpenMMLab. All rights reserved.
from .builder import build_optimizer, build_optimizer_constructor
+from .data_structures import * # noqa: F401, F403
from .evaluation import * # noqa: F401, F403
from .optimizers import * # noqa: F401, F403
from .seg import * # noqa: F401, F403
diff --git a/mmseg/core/data_structures/__init__.py b/mmseg/core/data_structures/__init__.py
new file mode 100644
index 0000000000000000000000000000000000000000..b73e72190a42a8920000c2523483b1d8ed35c55d
--- /dev/null
+++ b/mmseg/core/data_structures/__init__.py
@@ -0,0 +1,4 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+from .seg_data_sample import SegDataSample
+
+__all__ = ['SegDataSample']
diff --git a/mmseg/core/data_structures/seg_data_sample.py b/mmseg/core/data_structures/seg_data_sample.py
new file mode 100644
index 0000000000000000000000000000000000000000..23b60d5b6a25fce71728e4c5bf45eb5967af562c
--- /dev/null
+++ b/mmseg/core/data_structures/seg_data_sample.py
@@ -0,0 +1,92 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+from mmengine.data import BaseDataElement, PixelData
+
+
+class SegDataSample(BaseDataElement):
+ """A data structure interface of MMSegmentation. They are used as
+ interfaces between different components.
+
+ The attributes in ``SegDataSample`` are divided into several parts:
+
+ - ``gt_sem_seg``(PixelData): Ground truth of semantic segmentation.
+ - ``pred_sem_seg``(PixelData): Prediction of semantic segmentation.
+ - ``seg_logits``(PixelData): Predicted logits of semantic segmentation.
+
+ Examples:
+ >>> import torch
+ >>> import numpy as np
+ >>> from mmengine.data import PixelData
+ >>> from mmseg.core import SegDataSample
+
+ >>> data_sample = SegDataSample()
+ >>> img_meta = dict(img_shape=(4, 4, 3),
+ ... pad_shape=(4, 4, 3))
+ >>> gt_segmentations = PixelData(metainfo=img_meta)
+ >>> gt_segmentations.gt_sem_seg = torch.randint(0, 2, (1, 4, 4))
+ >>> data_sample.gt_segmentations = gt_segmentations
+ >>> assert 'img_shape' in data_sample.gt_segmentations.metainfo_keys()
+ >>> data_sample.gt_segmentations
+ (4, 4)
+ >>> print(data_sample)
+ <SegDataSample(
+
+ META INFORMATION
+
+ DATA FIELDS
+ gt_segmentations: <PixelData(
+
+ META INFORMATION
+ img_shape: (4, 4, 3)
+ pad_shape: (4, 4, 3)
+
+ DATA FIELDS
+ gt_sem_seg: tensor([[[1, 1, 1, 0],
+ [1, 0, 1, 1],
+ [1, 1, 1, 1],
+ [0, 1, 0, 1]]])
+ ) at 0x1c2b4156460>
+ ) at 0x1c2aae44d60>
+
+ >>> data_sample = SegDataSample()
+ >>> gt_sem_seg_data = dict(sem_seg=torch.rand(1, 4, 4))
+ >>> gt_sem_seg = PixelData(**gt_sem_seg_data)
+ >>> data_sample.gt_sem_seg = gt_sem_seg
+ >>> assert 'gt_sem_seg' in data_sample
+ >>> assert 'sem_seg' in data_sample.gt_sem_seg
+ """
+
+ @property
+ def gt_sem_seg(self) -> PixelData:
+ return self._gt_sem_seg
+
+ @gt_sem_seg.setter
+ def gt_sem_seg(self, value: PixelData) -> None:
+ self.set_field(value, '_gt_sem_seg', dtype=PixelData)
+
+ @gt_sem_seg.deleter
+ def gt_sem_seg(self) -> None:
+ del self._gt_sem_seg
+
+ @property
+ def pred_sem_seg(self) -> PixelData:
+ return self._pred_sem_seg
+
+ @pred_sem_seg.setter
+ def pred_sem_seg(self, value: PixelData) -> None:
+ self.set_field(value, '_pred_sem_seg', dtype=PixelData)
+
+ @pred_sem_seg.deleter
+ def pred_sem_seg(self) -> None:
+ del self._pred_sem_seg
+
+ @property
+ def seg_logits(self) -> PixelData:
+ return self._seg_logits
+
+ @seg_logits.setter
+ def seg_logits(self, value: PixelData) -> None:
+ self.set_field(value, '_seg_logits', dtype=PixelData)
+
+ @seg_logits.deleter
+ def seg_logits(self) -> None:
+ del self._seg_logits
diff --git a/tests/test_core/test_seg_data_sample.py b/tests/test_core/test_seg_data_sample.py
new file mode 100644
index 0000000000000000000000000000000000000000..c416e9ca679b66a4ed484cc42053f8fc7ef7b7c2
--- /dev/null
+++ b/tests/test_core/test_seg_data_sample.py
@@ -0,0 +1,77 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+from unittest import TestCase
+
+import numpy as np
+import pytest
+import torch
+from mmengine.data import PixelData
+
+from mmseg.core import SegDataSample
+
+
+def _equal(a, b):
+ if isinstance(a, (torch.Tensor, np.ndarray)):
+ return (a == b).all()
+ else:
+ return a == b
+
+
+class TestSegDataSample(TestCase):
+
+ def test_init(self):
+ meta_info = dict(
+ img_size=[256, 256],
+ scale_factor=np.array([1.5, 1.5]),
+ img_shape=torch.rand(4))
+
+ seg_data_sample = SegDataSample(metainfo=meta_info)
+ assert 'img_size' in seg_data_sample
+ assert seg_data_sample.img_size == [256, 256]
+ assert seg_data_sample.get('img_size') == [256, 256]
+
+ def test_setter(self):
+ seg_data_sample = SegDataSample()
+
+ # test gt_sem_seg
+ gt_sem_seg_data = dict(sem_seg=torch.rand(5, 4, 2))
+ gt_sem_seg = PixelData(**gt_sem_seg_data)
+ seg_data_sample.gt_sem_seg = gt_sem_seg
+ assert 'gt_sem_seg' in seg_data_sample
+ assert _equal(seg_data_sample.gt_sem_seg.sem_seg,
+ gt_sem_seg_data['sem_seg'])
+
+ # test pred_sem_seg
+ pred_sem_seg_data = dict(sem_seg=torch.rand(5, 4, 2))
+ pred_sem_seg = PixelData(**pred_sem_seg_data)
+ seg_data_sample.pred_sem_seg = pred_sem_seg
+ assert 'pred_sem_seg' in seg_data_sample
+ assert _equal(seg_data_sample.pred_sem_seg.sem_seg,
+ pred_sem_seg_data['sem_seg'])
+
+ # test seg_logits
+ seg_logits_data = dict(sem_seg=torch.rand(5, 4, 2))
+ seg_logits = PixelData(**seg_logits_data)
+ seg_data_sample.seg_logits = seg_logits
+ assert 'seg_logits' in seg_data_sample
+ assert _equal(seg_data_sample.seg_logits.sem_seg,
+ seg_logits_data['sem_seg'])
+
+ # test type error
+ with pytest.raises(AssertionError):
+ seg_data_sample.gt_sem_seg = torch.rand(2, 4)
+
+ with pytest.raises(AssertionError):
+ seg_data_sample.pred_sem_seg = torch.rand(2, 4)
+
+ with pytest.raises(AssertionError):
+ seg_data_sample.seg_logits = torch.rand(2, 4)
+
+ def test_deleter(self):
+ seg_data_sample = SegDataSample()
+
+ pred_sem_seg_data = dict(sem_seg=torch.rand(5, 4, 2))
+ pred_sem_seg = PixelData(**pred_sem_seg_data)
+ seg_data_sample.pred_sem_seg = pred_sem_seg
+ assert 'pred_sem_seg' in seg_data_sample
+ del seg_data_sample.pred_sem_seg
+ assert 'pred_sem_seg' not in seg_data_sample