Objective: To analyze the prevalence and changing trend of overweight and obesity among high school seniors in Beijing from 2009 to 2018, and to provide scientific basis for health and education departments to work out effective measures to prevent and control overweight and obesity among adolescents. Methods: The physical examination data of 700 588 high school seniors in Beijing from 2009 to 2018 were selected to describe the distribution characteristics of the detection rate of overweight and obesity, and to analyze whether there are differences in the prevalence of overweight and obesity among different genders and regions. Results: From 2009 to 2018, the prevalence rate of total overweight and obesity of high school seniors in Beijing showed an increasing trend by year ( χ 2=3.58, P <0.01). After 2016, the rising trend was more stable, and it declined for the first time in 2018. The prevalence of overweight ( χ 2=6 681.34, P <0.01) and obesity ( χ 2=15 663.08, P <0.01) were higher in male than in female. The prevalence of overweight and obesity in urban students was higher than that in suburban students (29.55%,27.95%; χ 2=211.43, P < 0.01 ), the prevalence of obesity in urban students was higher than that in suburban students from 2009 to 2013, and the prevalence of obesity in suburban students was higher than that in urban students from 2014 to 2018. The districts and counties with the highest detection rates of overweight and obesity are Shijingshan District (overweight: 19.06%, obesity: 13.99%), and the districts and counties with the lowest detection rates of overweight and obesity are Yanqing District (overweight: 13.48%, obesity: 7.18%). Conclusion From 2009 to 2018, the prevalence of overweight and obesity among high school seniors in Beijing has been increasing by year, and tends to be stable after 2016. Significant upward trend in obesity prevalence in suburban areas of Beijing has been observed.