Abstract: Objective To analyze the effect of coinsurance mechanism in social health insurance on health expenditure and on the health of Chinese urbanites,and to provide suggestions to social health insurance policy makers.Methods T-test methods and Logistic regression analysis approach were used with SPSS 13.0 to analyze the household data from 13 cities of 6 provinces in China.Results Compared medical expence paid by oneself with free health insurance,medical expenditure decreasesd by 60.6% in health people and 61.4% in unhealth population.There was a significant difference (P<0.05) in medical expenditure under different coinsurance rates;and different coinsurance rates also had a sizeable effect on people's health (P<0.05).The age,sex,education degree and income could also affect urbanite's health (P<0.05).Conclusion Higher co-insurance charges could reduce the use of medical care.However,it exerted harmful results in term of personal health.