Ripple is a typical power quality problem on the DC side of wind power converters, ripple resonance not only affects the power quality of the DC side, in severe cases, it will also endanger the safe and stable operation of wind power systems and their components. This paper introduces the application of film capacitors in the DC side of wind power converters and their actual equivalent circuit model; the influence of the stray parameters of the DC bus and film capacitor of the wind power converter on the ripple current on the DC side is investigated; the failure mechanism of the DC side capacitor of the wind power converter due to the ripple resonance is analyzed, the mathematical expression of its natural resonant frequency is derived. Finally, a simulation model of permanent magnet direct-drive wind power system considering stray parameters is built in Matlab/Simulink, the simulation results verify the theoretical analysis and the correctness of the model.