Objective To analyze the cut-off point of waist circumference (WC) for overweight and obesity in school children aged 7-14 in Haikou, and to provide a scientific basis for the formulation of prevention and treatment strategies for overweight and obesity in children. Methods Using the 2016-2019 ^“Student Health Record Management System in Hainan Province^”, 220 primary and secondary schools in Haikou were sampled using the PPS sampling method, and the height, weight and waist circumference of children aged 7-14 were collected and analyzed. Results A total of 283 054 children aged 7-14 years old were investigated. The average WC and percentile WC values of children in each age group were lower the national average WC values, and the WC continued to increase with age. The WC of boys was higher than that of the girls in all age groups (P < 0.0001), and the WC of urban children was higher than that of rural children of the same age (P < 0.0001). The WC cut-off points were P75-P80 (56.50-71.75 cm) in boys and P80-P85 (54.50-68.50 cm) in girls for overweight. For obesity, the WC cut-off points in boys of 7-11 years old and 12-14 years old were P85 (58.5-72.50 cm) and P90 (75.50-79.50 cm), respectively, and the WC cut-off points in girls of 7 years old and 8-14 years old were P85 (56.50 cm) and P90 (59.85-71.50 cm), respectively. Conclusion The cut-off points of WC for overweight are 56.50-71.75 cm in boys and 54.50-68.50 cm in girls, respectively. The cut-off points of WC for obesity are 58.50-79.50 cm in boys and 56.50-71.50 cm in girls, respectively. Except for the cut-off points for overweight in 7-year-old boys and 9-year-old girls and the cut-off points for obesity in 8 to 10-year-old girls before puberty, the cut-off points for overweight and obesity in other age groups are consistent with the national values.