In order to improve the pump beam homogeneity of high-power solid-state laser, the basic theory of beam homogenization with imaging and non-imaging beam integrator systems is analyzed. Mainly from three aspects, i.e., spot size, maximum incident angle and spot homogeneity, performances of both beam integrator systems are compared in detail. The analysis shows that imaging beam integrator system not only provides better homogenization effect and reduces the requirement of beam collimation than non-imaging beam integrator system, but also can change the distance between two microlens arrays in order to extend its applicable field. After passing through the imaging beam integrator system, the spot inhomogeneity of laser diode stacks is less than 10% in the illumination area.