For the overload problem of single controller in Software Defined Network (SDN), a game theory based master controller reselection mechanism-GAME-System Model (GAME-SM) was proposed. Firstly, the problem of switch migration constrained by resource was translated into maximizing revenue problem of zero sum game, and the GAME-SM mechanism was proposed. Secondly, the upper and lower thresholds of the controller load were set to determine the trigger conditions of the game, and the controller whose load reached the upper limit invited the neighboring controllers to participate in the game as game players. Finally, the game strategy was designed based on the zero sum game to maximize the revenue of each participant, and the master controller was reselected by the repeated game with the change of utility degree, and the load balance of the whole system was realized eventually. The simulation results show that the proposed mechanism can significantly improve the controller load balance, and the controller response time is reduced by 50% compared with Distributed-CoNTroLler (D-CNTL).