A total of 2818 children and adolescents were included in multifactor analysis, and we found that female [odds ratio (OR) = 0.68, 95% CI 0.49–0.81], living in rural area (OR = 0.68, 95% CI 0.56–0.82), age (OR = 0.95, 95% CI 0.92–0.98), high CRP concentration (OR = 1.08, 95% CI 1.04–1.12), and appropriate retinol level (OR = 1.32, 95% CI 1.09–1.59) were associated with obesity compared to low/normal BMI. The gene discussed is CRP; the disease is Obesity.