Abstract: In order to solve the problem of secondary frequency drop and the wind turbine stall of doubly-fed induction generator in the process of stepwise inertia control（SIC）,on the basic of the ramp type SIC,this paper establishes a mathematical model of the time in the linear decline phase related to the incremental power in the deceleration phase and the reduced power in the acceleration phase,calculating the maximum duration of the linear decline phase. The calculated maximum duration is used to avoid the wind turbine stall during the power linear decline phase,so as to provide the same frequency support capability as the ramp type SIC,while avoiding the wind turbine stall and reducing the second frequency drop. The simulations on a EMTP-RV platform of different disturbances,wind power penetration,and wind speed conditions are carried out to verify the effectiveness of the proposed method.