A microlens with a specific size is fabricated by using melting photoresist, and the microlens can be applied to a shortwave 1 μm ~3 μm infrared detector, which can effectively improve the photoelectric perfor-mance of the detector. Using AZP4620 thick photoresist and UV lithography technology, the lens production in the soft bake, exposure and development, hardening, hot melt and other processes were carried out in-depth and detailed experimental study was done to determine the optimal process parameters. The micro-lens with a crown diameter of (5.5 ± 0.5) μm and a radius of curvature of 3 μm was realized. The lens has good uniformity and consistency to meet the requirements of near infrared detection device.