Objective To explore the characteristics and changes of cognitive function after ischemic stroke and their relationship with changes of functional connectivity （FC） in resting-state functional magnetic resonance imaging （fMRI） in ischemic stroke patients after 3 months. Methods From September 2016 to February 2017， a total of 23 patients with post-stroke cognitive impairment （PSCI） in basal ganglia and 17 ischemic stroke patients in basal ganglia with no cognitive impairment （NCI） in the Cerebrovascular ward of Neurology Department of Beijing Tiantan Hospital Affiliated to Capital Medical University were recruited. At 2 weeks and 3 months after stroke， the cognitive function of the patients was evaluated and restingstate fMRI images were collected. Another 30 age， gender and education matched healthy volunteers were selected as the control group， and the cognitive function and restingstate fMRI data were collected. The changes of cognitive function and functional connection intensity at baseline and 3 months were compared， and the relationship between cognitive dysfunction and functional connection intensity after stroke was analyzed by multiple linear regression. Results At 2 weeks after stroke onset， the PSCI group showed significantly lower scores of total Auditory Verbal Learning Test （AVLT）， Rey-Osterreith Complex Figure （RCFT） -delayed memory， Boston Naming Test （BNT）， Verbal Fluency Test （VFT） and Symbol Digital Modalities Test （SDMT）， prominently longer time of Trail Making Test （TMT）-A， TMT-B and Stroop Color-Word Test （CWT） than those in the control group （P＜ 0.05）. Compared with NCI patients， the PSCI patients showed dramatically lower score of RCFT-delayed memory and longer time of TMT-A. At 3 months， the PSCI group exhibited significantly improved RCFT-delayed memory score than that in baseline （2 weeks after onset） （P＜ 0.05）. The PSCI group showed significantly lower FC in frontal lobe than that in baseline （GRF corrected，voxel P＜0.05，cluster P＜0.05）. The declined FA value in frontal lobe were positively related to the improved score of RCFT-delayed memory （GRF corrected，voxel P＜ 0.05， cluster P ＜ 0.05）. Conclusions In the patients with cognitive impairment after acute ischemic stroke in the basal ganglia， the intensity of functional connection in the frontal lobe increased significantly in the acute phase， and the scores of visual delayed recollection improved significantly in 3 months after onset compared with 2 weeks. The intensity of functional connection in the frontal lobe decreased gradually， which was related to the improvement of visual delayed recall.