Objective: To examine sleep quality and related factors among middle school students,and to provide a scientific reference for making the relevart interventional measures. Methods: A cross-sectional questionnaire anonymous survey was conducted among 9 560 students randomly selected from Shanxi province using multi-stage stratified cluster sampling. Pittsburgh Sleep Quality Index (PSQI) was used to collect information on sleep quality. Results: Among all the participants, 2 255 (23.6%) middle school students were reported poor sleep quality. The prevalence of poor sleep quality was significantly higher in girls (24.5%) than in boys (22.4%)(χ2=5.93, P<0.05). Significant differences were observed in the prevalence of poor sleep quality between junior middle school (12.9%), senior middle school (36.6%) and vocational school students (24.6%) (χ2=636.07, P<0.01). The global PSQI, sleep duration and sleep disturbance scores were higher in girls than in boys (t=3.76，8.38，3.47，P<0.01). There were significant differences between students with different school stages in global PSQI, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, use of sleeping medication, and daytime dysfunction scores (F=727.43,83.69,1 670.07,8.24,26.19,4.20,609.80,P<0.05). Multivariable Logistic regression analysis showed that gender, school stage, academic pressure, parental marital state, relationship with teachers, physical activity, smoking and drinking were associated with poor sleep quality among middle school students in Shanxi. Conclusion Sleep problems are common among middle school students, and appropriate intervention should be taken to improve sleep quality of students from individual, school-and family level.