Dynamic infrared scene simulation technologies play important roles in the performance evaluation of infrared imaging, tracking and guided weapon systems. The infrared scene simulation technology based on Digital Micromirror Device (DMD) is of most research value among infrared scene generation schemes. The gray modulation principle and operation mode of DMD are presented. On this basis, the DMD driver based on TI's 0.7 XGA DMD driver development platform is designed. The contrast of the infrared image is improved by magnifying the original image. Finally, a scheme for improving DMD projection frequency is proposed according to the integration time of detector output signals and the frame synchronization signals. The contrast of the gray level image projected by using this scheme is improved. The infrared imager can collect distinct gray images. Moreover, the display time of each gray image is reduced to 1.12 ms which is improved greatly compared with the 7.87 ms of conventional ways.