Abstract: Objective To explore the interactive effcts of family history of diabetes,diet and obesity on type 2 diabetes mellitus. Methods Totally 1 602 rural residents in Wangcheng county were investigated to collect information on their socio-demographics,family history of diabetes,diet structure,height,weight,waist-to-hip ratio,blood glucose,and other risk factors of diabetes.All significant risk factors in single-factor analysis were analyzed to find out additive interaction. Results The age-standardized morbidity of type 2 diabetes in the residents was 5.35%.Additive interactions were detected between family history and age≥45 years with a relative excess risk of interaction(RERI)of 6.299,between family history and central obesity(RERI=7.180),between family history and low education level(RERI=3.500),between family history and fatty diet(RERI=3.020),and between central obesity and fatty diet(RERI=6.642). Conclusion There are aditive interactions between family history of diabetes,diet and obesity as the risk factors for type 2 diabetes millitus.