From analyzing the effect of the atmospheric turbulence on laser communication system,based on the theory model of Rytov and Tartaskii and ignoring other noises in the system,the signal-to-noise ratio(SNR) and the bit error rate(BER) between which the relationship and intensity variance was deduced in laser communication system,then made numerical simulation which varied with distance in different turbulence and different wavelength.The result indicates that the intensity of atmosphere turbulence has great impact on both BER and SNR of the system,and it affects the former more.BER follows an exponential growth curve as the intensity of atmosphere turbulence increases initially and finally tends to be maintain the same value,during which course,the maximum effective range of the transmission varies.Adopting laser with longest wave to communicate can increase effective distance of the signal transmission and improve the quality of laser communication system.