Abstract: The considerable number of floating population exceeds the administrative regions corresponding to the pooling level of old-age insurance fund due to migration while the local management of old-age insurance system is ineffective in dealing with this problem, which results in the damage of old-age insurance rights of some floating population. The concrete manifestation of the loss of old-age insurance rights of part of floating population is low participation rate, difficult transfer and connection, and low benefit for old-age insurance. The coalition-proof equilibrium formed by the game among the central government, local government and employer provides an explanatory perspective for the incomplete old-age insurance rights of floating population. This paper develops and solves a mixed strategy game among central government, local government and employer, the results show that the central government should actively implement the reform of decentralization, regulation and service, appropriately reduce the old-age insurance expense paid by the employer, and improve the effectiveness of regulation, which is conducive to break the coalition-proof equilibrium in the protection of the old-age insurance rights of the floating population to enhance the governance modernization for old-age insurance of floating population.