Objectives:This paper tested the hypothesis of adverse selection and cost shift in the implementa -tion of health insurance portability policy and evaluated the impact to metropolitan health insurance funds .Methods:With data from health insurance information system in A city ,we used chi-square and t-test to test the variations be -tween transferredi-n group and transferred -out group, and we used multiple regression to explore the factors affecting reimbursement of outpatient costs and inpatient costs .Results:The chi-square test indicated that age and chronic dis -eases between transferred-in group and transferred-out group was statistically significant , and this proved that adverse selection existed in the health insurance portability .The t-test indicated that inpatient cost per capita and reimburse-ment of inpatient costs per capita between transferred i-n group and transferred -out group statistically significant.Mul-tiple regressions indicated that age and chronic diseases significantly affected reimbursement of outpatient and inpatient costs.Policy analysis showed that health insurance funds had rules of shift cost .Conclusion:Because of the effect of healthy migrants and risk-selection , the outpatient and inpatient costs of the transferred i-n group did not greatly influ-ence medical insurance funds .Therefore , local government should implement the portability policy boldly .