Objective: To explore the relationship between thalamic subregion volume changes and cognitive function in patients with cerebral small vessel disease (CSVD). Methods: 26 CSVD patients with cognitive impairment (CSVD-CI group), 24 CSVD patients with cognitive normal (CSVD-NC group), and 32 healthy controls (HC group) were included. Collect high-resolution magnetic resonance images of all subjects and perform voxel-based morphometric analysis to obtain the volume of thalamic subregions. Analysis of covariance (ANCOVA) was used to compare thalamic subregion volumes among the three groups, with age, sex, education and total intracranial volume as covariates. Pairwise comparisons were conducted using t-tests with False Discovery Rate (FDR) correction. Partial correlation analysis was further performed to evaluate the correlation between thalamic subregion volume and cognitive performance. Results: There were intergroup differences in the volumes of all subregions among the three groups. The pairwise comparison results showed that all thalamic subregions in CSVD patients exhibited volume atrophy compared to the HC group (all P < 0.05), while there was no significant difference in the volume of thalamic subregions between the CSVD-CI group and the CSVD-NC group (all P > 0.05). Partial correlation analysis showed that the volume of multiple thalamic subregions in CSVD patients was correlated with cognitive performance: executive function (Trail Making Test B) was negatively correlated with the volume of bilateral thalamic subregions (left ventral lateral dorsal nucleus, right anterior nucleus, and right ventral anterior nucleus) (all P < 0.05); The executive function (Stroop test 2) was positively correlated with the volume of the left thalamic subregion (ventral lateral dorsal nucleus, ventral anterior nucleus) (both P < 0.05); Verbal memory (5-minute delayed memory and recognition scores from the auditory language learning test) is positively correlated with the volume of the left thalamic subregion (pulvinar, ventral lateral dorsal nucleus, ventral anterior nucleus, ventral lateral ventral nucleus, etc.) (all P < 0.05). Conclusion: Extended atrophy of thalamic subregion volume is an important structural imaging feature of CSVD, and is associated with multi domain cognitive impairment (mainly including executive and memory). However, a single thalamic subregion volume index cannot effectively distinguish whether CSVD patients have cognitive impairment.