Abstract: Based on China Migrants Dynamic Survey data (2017)， this paper empirically analyzes the impact of medical insurance on the residence intention of floating population. It is found in the study that participating in the medical insurance in their current residence has the “lock-in” effect and increases the residence intention of floating population， while participating in the medical insurance in the place of domicile has the “pull-back” effect and reduces the residence intention of floating population. The “pull-back” effect and “lock-in” effect are strengthened with the improvement of the benefits level of medical insurances. Further analysis shows that the impact of medical insurance on the residence intention of floating population is restricted by flow distance. The “lock-in” effect of the insured in the place of residence and the “pull-back” effect of the insured in the place of domicile both increase gradually with the extension of flow distance. The government is supposed to continuously deepen the reform of medical insurance， simplify the reimbursement procedures in different places， improve the level of off-site reimbursement， and break the system barriers of geographical division to realize equal access to medical security rights by floating population.

Key words: floating population; medical insurance; residence intention; “lock-in” effect; “pull-back” effect