Fabrication of large depth microstructure by using thick film photolithography-technology is a considerable option, but effect of nonlinear distortion on the photolithography surface profile quality severely limits its application. For the above reason, a method to correct mask transmissivity function is proposed. The influences of nonlinear factors such as spatial imaging, propagation, exposure and development process are analyzed. Then, by utilizing the simulated annealing algorithm, transmissivity function of mask is optimized to improve the quality of surface profile of photolighography. Taking a concave cylinder lens as example, the simulated results of developed profile before and after correction are presented, and the volume deviation of profile after correction is only 2.63%. This method obviously improves the quality of surface profile, but does not increase difficulty of design and fabrication of the mask and expense, which is very useful to fabricate microstructure with high fidelity.