Abstract： Objective:To explore the joint association of education attainment and sedentary with insufficient physical activity in Kunshan, Jiangsu province.Methods:Multi-stage cluster random sampling method was conducted in 2016 in Kunshan City, physical activity levels were collected according to structure questionnaire, and multivariate logistic regression was used to identify factors associated with physical activity level. Logistic model was used to estimate interaction effect by the synergy index (S), the relative excess risk of interaction (RERI) and the attributable proportion due to interaction (AP).Results:Housework, traffic and regular exercise physical activity accounted for 10.23%, 41.84%, and 28.98%, respectively. Insufficient physical activity in total, male, and female population were 50.66% (95% CI: 49.04%-52.28%), 52.29% (95% CI: 49.94%-54.64%), and 49.29% (95% CI: 47.06%-51.52%). Multivariable logistic regression analysis demonstrated that high waist to hip ratio ( OR=1.12, 95% CI: 1.02-1.23), free of family history of hypertension ( OR=1.24, 95% CI: 1.14-1.36), newly diagnosed diabetes ( OR=1.35, 95% CI: 1.09-1.68), previously diagnosed diabetes ( OR=1.34, 95% CI: 1.07-1.69), awareness of waist ( OR=1.34, 95% CI: 1.21-1.48), and lower level of high density lipoprotein ( OR=1.14, 95% CI: 1.03-1.27) were positively correlated with insufficient physical activity. Moreover, high educational attainment ( OR=1.27, 95% CI: 1.10-1.46) and sedentary duration ( OR=1.37, 95% CI: 1.20-1.57) were associated with insufficient physical activity, and additive interaction was found between two factors on insufficient physical activity (RERI=0.367, 95% CI: 0.105-0.629. AP=0.183, 95% CI: 0.060-0.306. S=1.572, 95% CI: 1.079-2.289). Conclusion:Among permanent residents whose age between 18-69 years in Kunshan, insufficient physical activity is more prevalent, high education and sedentary are jointly associated with insufficient physical activity.