Abstract: Aiming at the problem of imaging distortion in DMD digital lithography system, a method to improve the imaging quality based on optimizing the DMD pixel gray is proposed. In the method, the mirror pixel gray are coded as binary mask with further sampled, and the mirror pixel gray are optimized with the gradient descent method. The lithography image of rectangular and T patterns are simulated, the pattern errors are reduced by 66.1% and 27.3%, respectively. The results show that this method can effectively improve the imaging quality.