Objective: To analyze the bidirectional association between sleep status and depressive symptoms among primary school students, so as to provide scientific evidence for developing targeted intervention and health education on children s mental health. Methods: In December 2021, 1 787 students in grades 2 and 3 selected from three primary schools in a district of Tianjin by a convenient sampling method were investigated in a baseline questionnaire survey, which was followed by a one year follow up in December 2022. The survey content included sociodemographic characteristics, lifestyle, etc., and the Children s Sleep Habits Questionnaire and the Center for Epidemiologic Studies Depression Scale for Children were used to assess students sleep quality, sleep duration, social jetlag and depressive symptoms. Linear regression model was applied to examine the association between sleep status and depressive symptoms score in primary school students, and cross lagged panel model was adopted to analyze the bidirectional association between sleep status and depressive symptoms. Results: At baseline, the sleep quality score among primary school students was 43.00(39.00, 47.00), the daily sleep duration was 9.42(9.12, 9.76) h, the social jetlag was 0.58( 0.29 , 0.92) h, and the depressive symptoms score was 5.00(2.00, 9.00). At the oneyear followup, the score of sleep quality among primary school students was 42.00(38.00, 47.00), the daily sleep duration was 9.43(9.12, 9.78)h, the social jetlag was 0.50 (0.25, 0.78)h, and the score of depressive symptoms was 4.00(2.00, 9.00). After adjusting for confounding factors such as gender, parental education level, and monthly family income, linear regression analyses showed that the baseline sleep quality score was positively associated with follow up depressive symptoms scores ( β =0.25) among primary school students, while baseline sleep duration ( β =-0.06) and baseline social jetlag ( β =-0.08) were both negatively associated with follow up depressive symptoms score (all P <0.05). Cross lagged regression models indicated that baseline sleep quality score positively predicted depressive symptoms score at the 1 year follow up ( β =0.10), and baseline depressive symptoms score positively predicted follow up sleep quality score ( β = 0.08 )(both P <0.05). Conclusions There is a bidirectional association between sleep quality and depressive symptoms among primary school students. Improving sleep quality may help alleviate children s depressive symptoms.