Abstract: Objective To explore secular trend of overweight and obesity prevalence among Chinese Tibetan students aged 7 to 18 years between 1991 and 2014,and to provide evidences for early prevention of overweight and obesity among the students and relevant policy making.Methods Based on the data from six waves of Chinese National Survey on Students Constitution and Health (CNSSCH)conducted in1991,1995,2000,2005,2010 and 2014,overweight and obesity among 7-18 years old Tibetan students were identified with the height-standardized weight method proposed by Research Group for Constitution and Health of Chinese Students in 1985.Secular trend and epidemic status of overweight and obesity among the students were described and compared by gender and age.Results From 1991 to 2014,the prevalence rate of overweight and obesity among the Tibetan students increased significantly from 1.01% and 0.42% in 1991 to 9.39% and 6.95% in 2014;the prevalence of obesity among the boy and girl students increased from 0.25% and 0.59% to 8.98% and 4.90%,with a 2 times higher increase ratio for the boy students compared to the girl students.The increasing percentage of obesity and overweight prevalence rate were 7.26 and 11.07,7.07 and 10.84,6.11 and 6.42,and 5.66 and 5.15 for the students aged 7-9,10-12,13-15,and 16-18 years old,respectively,between 1991 and 2014.The students at younger ages presented higher increased prevalence of overweight and obesity than the students at elder ages,particularly for the boy students.Conclusion The prevalence of overweight and obesity among Tibetan students in Tibet increased significantly between 1991 and 2014 and early intervention measures should be implemented among the students,especially among the pupils and boy students.