Objective: To investigate prevalence and influencing factors of overweight and obesity among children and adolescents in Jiangxi Province, and to provide the basis for strategies for prevention and treatment of overweight and obesity. Methods: Using stratified random cluster sampling ,a total of 77 780 primary and middle school students in 11 districts of Jiangxi Province were investigated with physical examination and questionnaire during March to November in 2019. Results: The detection rates of overweight and obesity of children and adolescents in Jiangxi province were 20.5% and 8.4%, respectively. Which decreased with the increase of the learning stage（ χ 2=178.65, 389.86）,with significantly higher in boys and urban areas （ χ 2=1 061.06, 504.21;56.17, 34.14）（ P ＜0.01）.In different economic areas, the detection rates of overweight and obesity in moderate economic area( 23.3 %, 9.7%) were the highest, followed by high economic area (21.1%, 8.7%) and low economic area(18.2%, 7.2%), and the differences were statistically significant（ χ 2=266.29, 143.90， P ＜0.01）.The results of multivariate Logistic regression analysis showed that in terms of social demography, overweight and obesity of children and adolescents in Jiangxi Province were associated with economic area, residence, learning stage and gender; in terms of dietary behavior, overweight of children and adolescents in Jiangxi Province was associated with consumption frequency of sugary drinks, sweets, fresh fruits and vegetables, and the influencing factors of obesity were consumption frequency of sweets and fresh fruits( P <0.05). Conclusion The situation of overweight and obesity of children and adolescents in Jiangxi Province is sorrisome, and comprehensive prevention and control should be carried out with the joint efforts of society, school and family.