Because the structure of Brillouin optical time domain reflectometer (BOTDR) is single-ended optical signal injection and the spontaneous Brillouin scattering signal is weak, signal-to-noise ratio (SNR) of the BGS is low.Two-dimensional (2D) image Gauss filtering algorithm is proposed to process BGS image to achieve noise reduction of BOTDR system.The noise signal characteristics of BGS acquired by BOTDR based on microwave heterodyne sweep method are analyzed, 2D image Gaussian filter BGS noise reduction algorithm is designed, experiments are carried out on BOTDR temperature measurement system, and the experiment verifies the noise suppression effect and signal processing efficiency of the proposed algorithm.Experimental proof that under the condition of 100 cumulative averages of a single frequency power curve, Gaussian filter algorithm is used to reduce the noise of 2D BGS image, and the SNR of BGS is improved by about 10.7dB after noise reduction, the fluctuation range of BFS in the variable temperature zone is reduced from ±7.79MHz to ±2.61MHz, at the same time, the effective sensing distance has been increased from about 13.8km to about 24.0km, the average signal processing time of noise reduction algorithm is about 0.129s.The results show that the method can significantly improve the SNR of BOTDR system and has good real-time performance.