A method to preprocess the CCD digital image of laser spot is proposed. 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 experimental results show that,the noise of original image is effectively suppressed and ridded after the preprocessing treatment, and the intensity distribution is comparatively smooth.