Abstract: In order to further suppress the over-voltage on the generator side caused by the high frequency pulse wave of the PWM converter of the permanent magnet wind turbine transmitted through the long cable and reduce the motor bearing current, a novel type of RLC-plus-C source passive filter and its design method is proposed in this paper. Firstly, an equivalent circuit model for long cable transmission is established, the overvoltage generation mechanism is analyzed, the transfer function is introduced, and the filter parameters are optimized. Secondly, the parameters of the novel filter R_f, C_c and C_f are designed. Based on this, a complete calculation method is designed in Matlab for the value of the inductance L_f. Finally, a simulation model of PWM converter-long cable-generator is built by Matlab/simulink software. A novel type of filter is introduced to analyze its overvoltage suppression effect, bearing current attenuation and power loss, and compare RLC with RL-C filters. The results show that the RLC-plus-C filter further suppresses the over-voltage at the machine end and significantly reduces the bearing current.