With the increasing demand for high-precision TFT-LCD products, especially when the large-scale production line of 8.5 generation and above produces small-scale products such as mobile phones, it is difficult to guarantee the exposure uniformity and overlay accuracy of color film exposure machine, which affects the development and production of high-precision TFT products. Through the research on the automatic compensation function of color film exposure machine, it is found that using the gap automatic compensation of the exposure machine, the difference value is automatically corrected to each shot, so that each shot exposure gap is closer to the actual gap, and the gap difference between shots is smaller, which can ensure the exposure uniformity. The actual shape of OT deformation can be more effectively compensated to get a shot shape more matching BM, which can improve the overlay accuracy. The color film exposure machine can ensure the exposure uniformity and overlay accuracy.