The principle and design theory of multi-aperture beam integration homogenizer are analyze.Diffracting and imaging microlens array laser beam homogenizers are designed to convert Gaussian beams into top-hat beams.The raytracing simulations show that both of them have good uniformity when the Fresnel-Number of microlens array is big,and imaging types give better uniformity and edge steepness than former.The collimation of incident beam has influence on beam uniformity.The big divergence of incident beam which exceeds the NA of microlens results in the side-lobe on the image plane,then the beam uniformity can′t be realized.