The traditional PWM algorithm and the flaws are introduced, the time sub-field is redistributed according to the human visual characteristics and an advanced PWM gray level algorithm is put forward. A DLP projector system is built based on FPGA and the block diagram and working principles are given. The feasibility of the algorithm is proved in the system. It is shown that after applying the enhanced PWM algorithm, the DMD switching frequency and the picture display are highly improved, the blink sensation is reduced and the stability of moving pictures are enhanced substantially.