Inverter PWM voltage output to the photovoltaic pump system caused by common-mode voltage, current etc. Phenomenon often cause trouble of water pump motor, the analysis of the PWM inverter drive motor system based on the mechanism of common-mode voltage, current, the dc side filtering capacitor common point connect back to the negative side LC filter, common mode voltage and current, be suppressed.LC filter changes the input state of the motor side, and the selection of filter parameters is optimized by analyzing the influence of PWM output LC filter method on the induction motor control system.The experimental results show that the method of parameter selection is correct and effective.