In order to study the effect of wavefront distortion on the beam pointing detection, the simulation analysis of beams is done with Monte Carlo method under the conditions of entire aperture and sub-apertures with different sizes and arrangements. The study results show that, when the root-mean-square of wavefront distortion is less than 0.163λ, the beam pointing detection error is under 0.5 μrad. When the root-mean-square of the wavefront distortion is less than 0.234λ, the beam pointing detection error is under 1 μrad. Sub-beam areas with relatively low wavefront distortion are suitable for calculating the beam pointing of an entire aperture.