Real-time grey-tone mask technique to fabricate the microstructures is presented in this paper. It combines the advantages of programmable digital LCD system and projection photolithography system, utilizing the LCD panel to display a serial of patterns which transfer light intensity distribution with representative of height information of 3D-profile into exposure time distribution. As a result, this continuous grey image on the recording plate is obtained. This technique principle is explained. Then based on partial coherent imaging theory, the process to fabricate the microlens has been simulated. As an experiment, the microlens array has been fabricated on panchromatic silver-halide sensitized gelatin with enzyme etching. The radius of microlens and etching depths are 59.33 μm and 1.638 μm, respectively.