Objective To explore the influencing factors of cognitive dysfunction after drug treatment of adolescent patients with depression. Methods The clinical data of 212 cases of adolescent depression hospitalized in Fuyang Third People's Hospital from January 2019 to April 2022 were analyzed retrospectively. According to the score of Montreal Cognitive Assessment （MoCA） after treatment， patients were divided into cognitive dysfunction free group （n=141， score of MoCA equal and over 26） and cognitive dysfuntion group （n=71， score of MoCA under 26）. The basic data of the two groups were collected and compared， including age， gender， body mass index （BMI）， course of disease， smoking history， family history， drinking history， Social Support Rating Scale （SSRS）， 17-Items Hamilton Depression Scale （HAMD-17）， educational level， type of depression attack. Receiver operating characteristic （ROC） curve was used to analyze the value of age and SSRS score in predicting cognitive dysfunction in adolescent patients with depression after treatment. Multivariate Logistic regression was used to analyze the risk factors of cognitive dysfunction in adolescent patients with depression after treatment. Results There was no significant difference in gender， BMI， course of disease， family history， HAMD-17 score and depression attack type between the two groups （P＞ 0.05）. The age and the rates of smoking， drinking and junior high school education patients in the cognitive dysfunction group was higher than those in the cognitive dysfunction free group， while the score of SSRS in the cognitive dysfunction group were lower than those in the cognitive dysfunction free group， and the differences were statistically significant （P＜ 0.05）. The areas under the ROC curve of age and SSRS score predicting cognitive dysfunction in adolescent patients with depression after treatment were 0.896 and 0.964， respectively （P ＜ 0.05）. Multivariate Logistic regression analysis showed that age between 14 to 18 years old （OR=1.571， 95%CI=1.251-1.973）， smoking （OR=1.457， 95%CI=1.187-1.788）， drinking （OR=1.254， 95%CI=1.093-1.439）， junior high school education level （OR=1.513， 95%CI=1.178-1.943）， SSRS score under 20 （OR=1.593， 95%CI=1.251-2.028） were the risk factors of cognitive dysfunction after treatment of adolescent depression （P ＜ 0.05）. Conclusions After the treatment of adolescent depression， cognitive dysfunction is affected by age， smoking， drinking， educational level and social support. Close attention should be paid to the prevention of cognitive dysfunction.