Grid frequency is an important variable which descripts load and generation balance. The frequency of grid is random. The traditional primary frequency modulation concentrates more on the single time, lacking of research and improvement from the statistical aspects. The conventional generator droop control is applied to primary frequency modulation to solve the problem of the non normal distribution. The proposed droop control strategy and non-dead zone traditional control strategy will switch according to the frequency of the grid. The generator won’t react frequently for there is on dead zone. Through theoretical analysis and simulation, it is demonstrated that the proposed method improves the frequency of power system and the problem of non normal distribution, which is beneficial to improve the system frequency stability.