The objective of the paper is to seek a more effective analysis tool for partial discharge (PD) studies. The paper begins with a brief definition of wavelets and the properties of two distinctive forms of wavelet transform, i.e. continuous wavelet transform (CWT) and discrete wavelet transform (DWT). The multiresolution-based pyramidal decomposition and reconstruction algorithm is stressed. Then the general advantages of wavelet transform over the traditional Fourier transform is summarized. The physical meaning of the phase-space domain or the result of CWT and DWT is also explained. Finally, applications of wavelet transform to partial discharge studies are explored.