At present, the influence mechanism of the frequency regulation dead zone on wind-storage joint frequency regulation is not clear. Also it is difficult to obtain the optimal frequency regulation dead zone parameters of the wind storage. Thus this paper analyzes the mechanism of wind-storage combined frequency regulation considering the dead zone of primary frequency regulation, and proposes an optimal dead zone parameter setting scheme. First, from the different frequency regulation characteristics of wind turbines and battery energy storage, a corresponding dead zone model is established, and a frequency response model considering the dead zone of primary frequency regulation of wind storage is established. Second, the influence of different characteristics inside and outside the frequency regulation dead zone and different input stages of wind storage on the dynamic frequency are analyzed, and then the time-domain expression of the maximum frequency deviation is determined segmentally. Then, to take into account both the effect and economy of frequency regulation, an optimization method of frequency regulation dead zone parameters based on the improved multi-objective particle swarm optimization (IMOPSO) algorithm is proposed. Finally, a simulation verifies the effectiveness of the proposed method when the dead zone parameters of primary frequency regulation of wind storage are set to 0.0579 Hz and 0.0386 Hz respectively.