Objective The purpose of this cross-sectional survey is to explore the current state of Internet addiction (IA) in Chinese medical students and its connection with medical students’ sleep quality and self-injury behavior. Methods Respondents were came from Wannan Medical College, China. The Young’s Internet Addiction Test, Pittsburgh Sleep Quality Index (PSQI), Self-Harm Questionnaire were used in this cross-sectional survey. A total of 3,738 medical students were investigated, 1,552 (41.52%) males, 2,186 (58.48%) females. T-test, chi-square test and MANOVA were used for data analysis. Results Of the 3,738 medical students, 1,054 (28.2%) reported having IA, 1,126 (30.1%) reported having poor sleep quality, 563 (15.1%) having self-harm behaviors. IA tends to be more female, upper grade students. The sleep quality of IA was worse than that of non-IA (χ2=54.882, p<0.001), and the possibility of self-injury was higher than non-IA (χ2=107.990, p<0.001). Conclusion This survey shows that the IA detection rate of medical students was 28.2%. Females, higher grade students had a higher IA detection rate. The low sleep quality and self-injury behavior of medical students are associated with IA.