Objective：To explore the factors influencing the incidence of stroke in an intervention population. Methods： A community based population aged 35 years old or over was cluster sampled from Shanghai Nanhui county. Individuals with at least one risk factor of stroke were selected to receive a cerebral vascular hemodynamic index （CVHI） examination. The patients with CVHI score below 70 were defined as high risk population and they received an intensive intervention based on general intervention for 3 years （1999-2001）. The present case control study included 402 stroke cases and 804 controls at high risk of stroke. The differences of CVHI were compared between 2 groups; the relationship between the studied factors and stroke was analyzed by univariate and multivariate Logistic regression. Results： The mean CVHI scores of case and control groups were 31.85±20.01 and 40.41±18.99, respectively （P〈0.001）. A significant dosage response was found between the decrease of CVHI score and the increase of stroke risk. Univariate analysis indicated that hypertension was the risk factor of stroke and taking key medication of intensive intervention was the protective factor of stroke, and their odds ratios （95% CI） were 2.43 （1.25,4.84） and 0.43 （0.33,0.55）, respectively. Multiple factors analysis showed that hypertension, taking key medication for intensive intervention, and screening by CVHI score were the independent influence factors of stroke. Conclusion： The primary risk factors of stroke are hypertension and the decrease of CVHI score; taking key medication of intensive intervention can markahly decrease the risk of stroke