Abstract: In order to solve the problem that the sensor signal is seriously disturbed by noise in a Brillouin optical time domain analysis (BOTDA) system based on Rayleigh scattering, the 2-D lifting wavelet transform algorithm was used to convert the measured signal from 1-D space to 2-D space, and the noise was reduced by threshold. Through the theoretical analysis and experimental verification, the traditional wavelet and 2-D lifting wavelet denoised data were obtained. The results show that the signal-to-noise ratio of the 2-D lifting wavelet transform is about 10dB higher than that of the traditional wavelet transform, and the computation amount is reduced by 1/3. The 2-D lifting wavelet makes full use of the time correlation of the measured signal, the transformation structure is simple, the operation speed is quick and the noise reduction effect is superior to the traditional wavelet. It is suitable for noise reduction in a Rayleigh BOTDA system. The results of this paper are of great reference to the research of signal denoising in optical fiber sensing systems.