The study evaluates the depressive symptom score and cognitive ability of elderly patients with depression,elaborates the interaction between the severity of depressive symptoms and cognitive function,deeply explores the relationship between the two,selects 76 elderly patients with depression as research objects,evaluates the depression score and cognitive function level of elderly patients with depression with Questionnaire survey,Geriatric Depression Scale(GDS)and Simple Intelligence Test Scale(MMSE),and explores their correlation.Evaluation results show that the impairment of cognitive ability is more obvious in female patients,age>70 years old and patients with education below primary school(P<0.05).The depression scores of elderly patients with depression after 1 month of treatment is significantly lower than those before treatment(P<0.05).Orientation,attention computing,memory,recall,language ability and total score of elderly patients with depression are significantly higher than those before treatment(P<0.05).The results of Pearson correlation coefficient comparison show that depression score in elderly patients with depression is negatively correlated with a single index of cognitive function,indicating that there is a close relationship between the severity of illness and cognitive function impairment in elderly patients with depression.With the remission of depressive symptoms,cognitive function can be significantly improved.