An analysis-based approach to fault diagnosis of an inverter circuit is easily affected by noise interference,and the accuracy of fault diagnosis affected too.An improved signal processing method for variational modal decomposition(VMD)was proposed.Through the sparrow search algorithm to opti-mize the parameters in the traditional VMD and decompose the current signal according to the optimal parameters,the optimal denoising effect could be obtained.Compared with wavelet transform,empirical mode decomposition and other signal processing methods,the error evaluation index was used to eval-uate the denoising effect,and the power spectrum graph image was more intuitively reflected in the fre-quency domain.The experimental results showed that the proposed method could effectively reduce the noise content and the error of frequency detail feature was less than 4%,verifying the effectiveness and feasibility of the method.