Objective: To investigate the correlation between sleep quality and the use of smart phone before bed in middle school students, and to provide a reference for relevant prevention and control. Methods: A total of 3 749 students from 4 middle school which were randomly selected by stratified cluster sampling method were assessed with selfdesigned questionnaire for the students’ general information,smart phone usage before bed,as well as the Epworth Sleepiness Scale(ESS),and Insomnia Severity Index(ISI). Results: A total of 63.17% of students in the seventh grade used mobile phones before going to bed. 67.04% in the eighth grade, 81.18% in the ninth grade, 83.54% in the first grade of high school and 80.11% in the second grade of high school. Mobile phones usage before bed gradually increased with grade. Students with ≥2 h smart phone usage before bed(group 2) had higher scores than those with <2 h smart phone usage before bed(group 1) in each item of ESS, except dozing during traffic jam(P<0.01). The group 2 had higher scores than group 1 in ESS and ISI scores(P<0.01). Conclusion Smart phone usage before bed in middle school students is very common. The risk of sleep disorders increased with the duration of smart phone usage before bed. Parental supervision should be involved in the intervention of smart phone usage before bed among middle school students.