Objective: To analyze the trends of overweight and obesity in children and adolescents aged 7-18 in Hainan Province from 2005 to 2019, in order to provide a scientific basis for prevention strategies. Methods: Data were sourced from a total of 42 811 students in Hainan Province in 2005, 2010, 2014 and 2019 for physical fitness and health investigation, according to the criteria of Screening for Overweight and Obesity among School aged Children and Adolescents. The linear trend of overweight and obesity was compared by using the χ 2 test and χ 2 trend test, and with 2005 as the base period, the dynamic analysis was conducted to compare the growth and development rates of overweight and obesity. Results: The detection rates of overweight in children and adolescents aged 7-18 in Hainan Province were 4.7%, 5.1%, 6.7% and 10.8% in 2005, 2010, 2014 and 2019, respectively, while the detection rates of obesity were 2.7%, 2.4%, 2.5% and 6.8%, which showed an overall upward trend by year ( χ 2 trend =370.57 , 313.55, P <0.01). All differences in overweight and obesity detection rates across gender, ethnicity, and age groups were statistically significant for each year ( χ 2=9.56-290.95, P <0.01). And the detection rates of overweight and obesity increased linearly over year in different characteristic groups ( χ 2 trend =29.92-280.11, P <0.01). The annual growth rate of overweight detection rate was higher for girls (6.4%) than for boys (6.1%), higher for ethnic minorities (7.1%) than for Han (5.7%), and higher for the 16- 18 age group (8.4%) than for the 7-9 (3.6%), 10-12 (6.2%), and 13-15 age groups (7.7%). And the annual growth rate of obesity detection rate was higher for boys (8.1%) than for girls ( 5.7% ), higher for ethnic minorities (7.1%) than for Han ( 6.8% ), and higher for the 16-18 age group (77.2%) than for the 7-9 (2.8%), 10-12 (8.2%), and 13-15 (18.7%) age groups. Conclusions The overall prevalence of overweight and obesity among children and adolescents aged 7-18 in Hainan Province continues to increase from 2005 to 2019, with differences in genders, ethnic and ages. Interventions should be implemented to reduce the incidence of overweight obesity in children and adolescents.