Research results of microlens beam shaping and homogenizing optical system for the 248 nm excimer laser are reported. Through the actual filming, an excimer laser light energy distribution color image is obtained. Matlab is used to analyze the image and extract relevant information to calculate. Then an actual energy distribution of excimer laser light source is simulated by the optical software ZEMAX. According to the characteristics of the light energy spatial distribution, a microlens beam shaping and homogenizing optical system for the 248 nm excimer laser is designed and fabricated. The experimental results are in good agreement with the theoretical simulations. After the shaping and homogenizing, a high uniform beam spot is obtained finally. The profile of this spot is a standard square with a size of 18 mm × 18 mm. The energy uniformity error (process window) of the beam spot is less than ± 2% , and the top- hat factor of energy distribution is about 0.90. This optical system can transform 85% of the total input beam power into the work plane of output beam. The spot shape of original excimer laser is irregular, and the energy distribution is nonuniform. This technical scheme can be a good solution to these problems. The successful development of this optical system has independent intellectual property rights, and also provides a technical support for the excimer laser micromachining with high quality and efficiency.