Objective? To explore the relationship between cerebral arterial blood flow velocity and cognitive function in patients with depression after antidepressant therapy. Methods? A retrospective analysis of the clinical datas of 76 patients with depression treated in The Third People's Hospital of Taicang from December 2018 to December 2020, acted as the depression group, and treated with the antidepressant Paroxetine Hydrochloride tablets for 6 weeks. In addition, the physical examination datas of 68 cases healthy subjects who underwent physical examination at the same period were retrospectively analyzed and acted as the healthy control group. Transcranial Doppler ultrasound was used to detect the blood flow velocity of various cerebral arteries of subjects in the two groups. Compared the average cerebral arterial blood flow velocity, the digital cancellation test (CT), and the Wisconsin Card Sorting Test (WCST) score of patients in the depression group before and after treatment and the subjects in the healthy control group; analysed the correlation between the average cerebral arterial blood flow velocity and the total net score of CT score and the total number of WCST error responses of patients in the depression group after treatment.Results? Compared with before treatment, the mean blood flow velocity of basilar artery of patients in the depression group increased significantly after treatment; compared with the healthy control group, the mean blood flow velocity of basilar artery, left middle cerebral artery, right middle cerebral artery, left anterior cerebral artery and right anterior cerebral artery of patients in the depression group reduced significantly after treatment; compared with before treatment, the net score Ⅰ , net score Ⅱ , net score Ⅲ , net score Ⅳ , net score Ⅴ , total net score of each item in CT score of patients in the depression group increased significantly after treatment, but all items after treatment CT scorewere still significantly lower than the healthy control group; compared with before treatment, the number of error responses and the number of persistent errors of patients in the depression group after treatment were significantly lower than before treatment, and the WCST score were still significantly lower than those of the healthy control group after treatment (all P<0.05); the total net score of CT score was positively correlated with the blood flow velocity of the basilar artery, left middle cerebral artery, right middle cerebral artery, left anterior cerebral artery,and right anterior cerebral artery (r =0.281, 0.431, 0.382, 0.634, 0.283, all P<0.05); the number of error responses was positively correlated with the blood flow velocity of the basilar artery, left middle cerebral artery, right middle cerebral artery, left anterior cerebral artery, and right anterior cerebral artery (r =0.352, 0.521, 0.328, 0.312, 0.302, all P<0.05). Conclusion After short-term treatment with antidepressants, the attention, executive function, cognitive function and arterial cerebral blood flow rate of depression patients can be relieved to a certain extent,but it still shows abnormality compared with healthy people, there is a positive correlation between the improvement of cerebral arterial blood flow speed and the recovery of attention, executive function and cognitive function, clinically, the severity of depression can be judged by the degree of cognitive impairment in patients with depression, relevant functional training and treatment can be taken to improve the cognitive function of the patient and relieve the condition.