By focusing laser pulses with wavelength 1064 nm and pulse width 8 ns into FC-72 medium,the intensity distribution of backward stimulated Brillouin scattering (SBS) spot is investigated experimentally by CCD camera. The images are analyzed by digital image processing technology to obtain the spatial intensity profile and evolution of SBS spot. Using the image processing toolbox of MATLAB,the noise removing treatment on original CCD image of laser spot is performed. And the smoothing treatment on intensity distribution curve is achieved by using the curve fitting and FFT smoothing functions of Origin software. The results show that the noise of original image is effectively suppressed and ridded after the preprocessing treatment,and the intensity distribution is comparatively smooth. On the condition that the pump beam is of Gaussian profile,the intensity distribution of SBS spot is changed from quasi-Gaussian to Gaussian profile when the pump energy increases.