Little information is available on the trends in severe pediatric obesity in China. Therefore, we aimed to examine the trends in overweight, obesity, and severe obesity in Chinese children from 1991 to 2015. Overall, 17,004 children aged 6-17 years were included in this study, which was based on the China Health and Nutrition Survey 1991-2015. We defined overweight [BMI ≥85th percentile], obesity (BMI ≥95th percentile), and severe obesity (BMI ≥120% of the 95th percentile, or 35 kg/m) according to the U.S. Centers for Disease Control and Prevention Growth Charts. Controlling for age, sex, and region, we performed multivariate analyses to assess secular trends in the prevalence of overweight, obesity, and severe obesity in the pediatric population. During 1991-2015, the prevalence of overweight increased from 4.6% to 21.1%, of obesity from 1.4% to 10.1%, and of severe obesity from 0.2% to 4.0% (relative increases of 358.7%, 621.4% and 1900.0% in overweight, obesity, and severe obesity, respectively). We observed a significant positive trend in the prevalence of overweight, obesity, and severe obesity in the pediatric population [odds ratios (95% confidence intervals): 1.23 (1.21, 1.26), 1.30 (1.26, 1.34), and 1.52 (1.41, 1.63), respectively; all < 0.001]. These results did not differ significantly between subgroups of sex, age, and region, or when Chinese national reference standards were used. The prevalence of childhood overweight, obesity, and particularly severe obesity in China increased significantly from 1991 to 2015.