In order to effectively remove electromagnetic interferences in transformer partial discharge (PD) signals, this paper proposes applying a new signal decomposition algorithm——variational mode decomposition (VMD) and wavelet to transformer PD signal to suppress the periodical narrow-band interferences and white noise because of the problems of empirical mode decomposition such as modal aliasing. Firstly, VMD can decompose noisy signal into several modes, which are compact around a center pulsation respectively, and the white noise is automatically filtered out in the decomposition process; then, extract modes which contain PD information for reconstruction and finally, remove residual periodical narrow-band noises by wavelet denoising so as to realize interference suppression. The analysis results of simulations and measured signals show that the proposed method can eliminate two kinds of interferences well and retain the PD characteristics, verify that the approach which uses VMD and wavelet to remove the interferences is efficient and thus it is fit for PD signal denoising.