In intersatellite communications, wave front aberration is main factor in affecting far-field behavior of signal beam. In this paper the influence of coma and spherical aberration on the far-field distribution and antenna receiving power is analyzed, in which aberration attenuation factor is introduced and the relation of it to root mean square (RMS) of wavefront aberration is given. The results show that the deeper coma and spherical aberration are, the heavier the influence on receiving power is. In the condition of the antennae being aligned correctly, receiving power becomes half of that for signal beam without aberration, when the values of root mean square for coma and spherical aberration are 0.120λ and 0.135λ, respectively. The influence of coma on receiving power is mainly caused by the moving of the intensity peak, and for spherical aberration it is the increasing of secondary intensity peak.