LED array light sources are widely used in medicine, micro-nano processing, optical imaging, and other fields due to their high brightness, long life, energy savings, and environmental protection. However, their homogenization system has issues such as difficult light collimation and small achievable illumination spot area, making them difficult to be widely used in the optical field that requires uniform illumination. To address this issue, this paper proposes a microlens array based large-area LED array light source homogenization method. First, the theoretical analysis is performed by matrix optics and near-axis optics theory, and then the system design and simulation experiments are conducted by using light tools software. Finally, a large-area of the uniform spot is achieved on the image surface.Compared with the previous homogenization system, which can achieve up to 50 mm×50 mm, the homogenization system can achieve a uniform spot of 104 mm×104 mm, and uniformity of 87.375% of the large-area rule. This method is of great significance systems that require large-area uniform illumination in the fields of medicine, infrared night vision, projection display, and aerial lighting.