Laser imaging tracking system is a potential way of tracking dark target in distance especially in space, but target image under the illumination of laser is modulated by the laser speckle and it will affect the identification and orient precision of target. Analysis of the statistical characteristics of laser imaging is given, a combined numerical filter depressing the image noise that utilize gray level linear transformation, median filtering and Lee filtering acting on the original image in turn is provided. The results indicate that the noise coefficient is reduced from 0.67 to 0.22, and edge-preserving degree is up to 0.96, respectively, and it makes a necessary basis for the following image processing.