Abstract: Objective To explore the the situation of dropout of the drug users receiving methadone maintenance treatment (MMT) and its related factors in Zhaojue County, Liangshan Prefecture. Methods A retrospective cohort study was conducted on drug users enrolled from MMT clinics in Zhaojue County and who had only one treatment stage from January 1st, 2013 to December 31th, 2015. Descriptive method was used to describe demographic characteristics, drug use behaviors, etc. Factors affecting the situation of dropout were analyzed by survival analysis. Results A total of 301 drug users were included in this study, the average duration of the drug users receiving MMT was 14.5±10.7 months, and the median was 15.1 months. By the end of observation period, the rate of patients who withdrew from MMT was 85.38% and the rate of patients whose retention time was more than 1 year (including 1 year) was 56.48%. Cox proportional hazard regression modeling determined that the situation of dropout was associated with education level, the period of drug use, the history of injecting drug use and daily dosage (all P<0.05). Conclusions There were more than half of maintenance treatment patients adhered to the period that MMT had an effect. In the later process, corresponding measures, such as increasing daily dosage, enhancement of education, psychological counseling and behavior intervention, should be taken to prolong retention time.