Abstract: Proceedings from the theory of geometric optics,the condition adaxial noncoherent imaging of Fizeau opticalsynthetic aperture imaging system is derived to achieve diffracion limited performance over a finite field of view,and the conclusion is that the angular magnification of the individual telescope must be equal to the linear demagnification factor.So telescope with a special aperture diaphragm so as to teproduce exactly the ensemble of a collecting telescope.Then,the constraint to Fizeau optical synthetic aperture imaging system is achieved.