Objectives The aims of this study were to assess the associations between parity and metabolic syndrome(MetS)and its components and to evaluate the effects of body mass index(BMI)on these associations.Methods A total of 5,674 women were enrolled from Jidong and Kailuan communities(Tangshan,Hebei)in North China.All participants completed standardized questionnaires,physical examination,and biochemical measurements.Logistic regression analysis was used to test the associations.Results Compared with women with parity of one,nulliparous women had decreased odds ratios(ORs); those with parity of two had odds of abdominal obesity [OR =1.45,95％confidence interval(CI)1.17-1.81,P＜0.001],high blood pressure(OR =1.26,95％CI: 1.03-1.54,P=0.025),elevated fasting glucose levels(OR =1.36,95％CI: 1.03-1.79,P=0.029),and MetS(OR =1.39,95％CI: 1.13-1.73,P=0.002); and those with parity of three or more had increased odds of elevated triglyceride levels(OR =1.42,95％CI: 1.04-1.94,P=0.027)and MetS(OR =1.50,95％CI: 1.10-2.05,P=0.011)after complete adjustment for confounders.Furthermore,BMI and age subgroups partially modified the associations between parity and MetS and its components.Conclusions Parity is positively associated with MetS and select components in women.BMI is an important modifier involved in the associations between parity and MetS.