Abstract: With the increasing penetration of renewable energy,wind turbines based on doubly fed induction generators（DFIG） are becoming more and more important in the power system.The direct power control（DPC） without phase-locked loop（PLL） can improve the dynamic response capability of DFIG,and avoid the influence of PLL on the dynamic ability of power control.Aiming at the stability performance of the DFIG system based on DPC without PLL connected to the weak grid,the impedance of DFIG system based on DPC without PLL was developed,and the frequency coupling characteristics in the whole frequency band was analyzed.Therefore,an equivalent single-input single-output（SISO） impedance model was developed to achieve the parameter sensitivity analysis considering the control parameters and operation condition.Finally,the simulation model was developed to validate the developed model and analysis by simulation results.