The intensity distribution of diode laser is not uniform due to the broad-area and ridge-waveguide designs, the poor beam quality is the limiting factor of applications. In order to achieve homogenized spot by the beam shaping of high-power diode laser stack, a homogenization system for diode laser stack beams based on microlens array is designed. The diode laser beam shaping theory and process of microlens array are analyzed. The lower limit of clear aperture of microlens is confirmed by the analysis of the impact of the diffraction of microlens edge on the spot homogeneity. The intensity angle distribution of spot is defined by paraxial matrix optical analysis. The simulation and experimental test are carried out for the microlens array beam shaping system, realizing the spot with the homogeneity of 91.89%.