diff --git a/mmdet/core/bbox/samplers/combined_sampler.py b/mmdet/core/bbox/samplers/combined_sampler.py
index 578abe36004f276820d8240ac8574e631cb17c49..8de85aeafe1c5e902d742844c57f9120f9e0fceb 100644
--- a/mmdet/core/bbox/samplers/combined_sampler.py
+++ b/mmdet/core/bbox/samplers/combined_sampler.py
@@ -1,5 +1,3 @@
-from mmcv.runner import obj_from_dict
-
 from .random_sampler import RandomSampler
 from ..assign_sampling import build_sampler