Abstract: In order to investigate the effects of aperture averaging on the space laser communication system, the fading statistics of transmitted beam are deduced and evaluated, which include scintillation index, probability of fade, number of fade and mean fade time. The results show that the scintillation index, probability of fade, number of fade and mean fade time would be decreased significantly as the receiver aperture increases. The system performances can be improved, especially in the case of strong turbulence due to the small parameters. Based on the methods and the results, the effects caused by aperture averaging on the space laser communication systems can be predicted and estimated effectively.