Active laser imaging system, which can be of high resolution, anti-interference and three-dimensional (3-D) imaging, has been used widely. But its imagery can be disturbed by speckle and some other Gaussian noises. Speckle noise is a kind of multiplicative noise and the Gaussian noise is additive noise, and which noise on the dominating status is very important for building the model of noise suppression. So, in the paper, the statistic characteristics such as probability curve and gray mean variance ratio etc. in the imagery disturbed by speckle and some other Gaussian noises are analyzed firstly, then the different statistic characteristics effected by the two kinds of noises respectively are found. Based on these characteristics, the images of active laser imaging system are discussed, then the results show that the most imagery noise is speckle. At the same time, the speckle noise variance in this imagery is calculated.