The fly′s eye integrator is widely applied in homogeneous illuminance, but its performance decreases dramatically when the aberration of the system is large. In order to study the effects of aberration, the fly′s eye integrator is supposed to be composed by some certain sub-imaging-systems. The point diagram of grim point, distortion and the departure of sub-image location caused by aberration can influence the performance of fly′s eye integrator seriously, but the point diagram of inner points can improve the performance to some extent. At last, an example, which optimizes a fly′s eye integrator made up of two ordinary lens rather than Fourier lens by limiting the derivative of aberration, is given and validates the effectiveness of the imaging analysis and its result.