Objective: To explore the relationship between left-behind experience, sleep quality and depression in college students and to provide a scientific reference for improving mental health of college students. Methods: The stratified cluster sampling method was used to investigate depression and related factors among undergraduates at two universities in Qiqihar City from November to December 2018, and the effects of left-behind experience and sleep quality on depression were analyzed. Results: Depression detection rate of college students in Qiqihar City was 30.62%, there was no difference in the detection rate of depression among college students of different sex( χ 2=3.15, P >0.05), depression detection rate of college students from rural area was higher than in urban students, non-only child higher than onlychild( χ 2=8.61, 8.98, P <0.05). Multivariate Logistic regression showed that left-behind mode, left-behind age, type of stay-at-home, frequency of contact with parents during stay, and sleep quality were associated with depression( OR =0.28-6.00, P <0.05). Conclusion Depression of college students is associated with previous left-behind experiences and sleep quality.