For the problems of reduced secrecy rate and energy according to noncooperation of selfish relay, this paper presents a security coalition method based on the game theory. Firstly, this paper introduces a benefit-sharing mechanism of cooperative game for the adaptive security coalition method, and models the transmitter coalition. And then this paper makes the increased part of total network secrecy rate compared with the initial as the transferable benefit, and allocates it to all transmitters in the coalition. After that, the transmitters iterate through the average utility under all coalitions, and find the largest benefit coalition. Finally, this coalition of transmitters is formed autonomously, the transmitter which is badly in need of sending signal or the transmitter with the worst eavesdropping channel conditions under the same need sends signal, the rest cooperate by sending artificial noise. Simulations and analyses show the fairness and effectiveness of this method, when sending power is 20 mW, the average network secrecy rate under the Gaussian channel compared with the initial stated is improved by 1.8 .