On the basis of symmetry of optical systems, the effects of several kinds of complex pupil constructions on an incoherent synthetic aperture imaging optical system were analyzed and compared. Firstly, the two-dimensional Point Spread Function(PSF) and two-dimensional Modulation Transfer Function(MTF) were used to analyze the complex pupil optical system, and it is concluded that the symmetry of complex pupil distribution has effects on the symmetries of PSF and MTF. Then, for practical pupil distribution, the two-dimensional PSFs and MTFs of the common synthetic aperture optical systems as follows, Golay3, Golay4,JWST and GMT, were given by optical design software Zemax and Matlab, and the symmetry of the systems was compared by combining the spatial distribution of MTF. Obtained results indicate that JWST and GMT synthetic aperture systems developed recently show 30 and 9 MTF symmetric axes ,respectively, which is obvious higher than 3 MTF symmetric axis of a common Golay3 construction. Moreover, their MTF distribution is more reasonable. These results demonstrate that the good symmetry of pupil distribution has a better imaging for the incoherent imaging optical system with a complex pupil.