Objective: To analyze the interaction of fat mass (FM) and fat free mass (FFM) on the aggregation of cardiovascular disease risk factors (CVRFs) among children and adolescents in Yinchuan City, China, so as to provide scientific basis for the prevention of CVRFs and cardiovascular disease in children and adolescents. Methods: A total of 1 822 children and adolescents aged 12 to 18 years in Yinchuan City were randomly selected for questionnaire survey, physical examination, body composition assessment and laboratory tests, through a cluster sampling method from 2017 to 2020. Binary Logistic regression was used to analyze the relationship between FM, FFM and the aggregation of CVRFs, and their interaction was analyzed. Results: After adjusting for sex and age, the risk of having CVRFs aggregation ≥1 in high FM and low FFM group and high FM and high FFM group was 2.01(95% CI =1.46-2.77) and 3.64(95% CI =2.66-4.98) times higher than that in low FM and low FFM group, and the risk of having CVRFs aggregation ≥2 was 1.67(95% CI =1.06-2.63) and 4.20 (95% CI =2.76-6.38) times, respectively( P <0.05). There was a multiplicative interaction between FM and FFM, which increased the risk of CVRFs aggregration ≥1 and ≥2. The adjusted OR and 95% CI were 1.58(1.04-2.40) and 1.95(1.12-3.42), respectively( P <0.05). Conclusion The results indicated the additive and multiplicative interactions between high levels of fat mass and fat free mass on the aggregation of cardiovascular risk factors, which increased the risk of aggregation of cardiovascular risk factors.