To solve the waveform distortions and the bad performances of threshold methods and traditional singular value decomposition（SVD） methods for periodic narrow-band noise rejection of partial discharge（PD）

this paper presents a noise suppression method based on the improved SVD algorithm with guide signals. Firstly

the number of periodic narrow-band noise is determined by the classic threshold method combined with mixed PD signals fast Fourier transform（FFT） power spectrum

and a frequency estimation method based on three FFT sampled values is proposed to estimate the interference frequency accurately. Then the guide signals are structured and added to mixed PD signals to separate the singular value of narrow-band noise from that of PD signals

leading to suppression of narrow-band noise. The simulation and experiment results show that the proposed method can suppress narrow-band noise effectively and show the original PD signals waveform. Compared with traditional SVD methods and FFT denoising methods

the method proposed in this paper has better denoising results.