In the noisy environment, the highly complete extraction of cable partial discharge signal is the key to the research of cable insulation on-line monitoring. In this paper, a partial discharge signal denoising method based on improved EEMD is proposed. Firstly, EEMD decomposition is carried out on the original partial discharge signal, Fourier transform is carried out on each order modal component (IMF) decomposed, and its corresponding amplitude variance is calculated as the threshold. Combined with the local weighted regression scatter smoothing algorithm, the IMF component mixed with noise and effective signal is filtered. Finally, it is superimposed and reconstructed with the IMF component of pure PD signal to obtain the filtered partial discharge signal. Through simulation and laboratory data analysis, the signal-to-noise ratio and waveform similarity coefficient of partial discharge signal after noise reduction are improved, which proves the effectiveness of the noise reduction method proposed in this paper.