Objective To investigate the sleep quality of students from a medical university and to analyze the risk factors of sleep disorders. Methods Students from a medical university were selected with cluster sampling method. A total of 886 students were included in this study: there were 55 Major A students, 80 Major B students, 97 Major C students, 577 Major D students, and 77 Major E students. The students were investigated by Pittsburgh sleep quality index (PSQI) and self-designed physical state questionnaire. Results (1)The number of effective questionnaire was 843 and sleep disorders were found in 284 students, with an incidence of 33.7% and a PSQI score of 5.48±0.12. The incidences of sleep orders and PSQI scores were 43.4% (23/53) and 6.23±0.48 for Major A, 32.9% (23/70) and 4.93±0.44 for Major B, 40.4% (36/89) and 5.75±0.34 for Major C, 32.4% (183/564) and 5.47±0.14 for Major D and 28.4% (19/67) and 5.18±0.40 for Major E, with no significant difference found for different majors (P>0.05). (2)The factors leading to somnipathy included emotional stress, ambient noise, somatic pain, school learning, seldom late-night snack and occasional late-night snack (OR=0.577, 0.611, 0.265, 0.260, 0.547, and 0.507, respectively). Conclusion The students in the involved medical university have a low sleep quality which may affect their physical state during day time. Active measures should be taken to improve students sleep quality so as to insure their study.