In the TFT manufacturing process, the exposure process directly affects the quality of the final pattern of the film. In order to analyze and solve the exposure Mura problem, it is necessary to investigate and study the lighting phenomenon of the panel and manufacturing process. Firstly, the cause of failure was investigated by scanning electron microscope analysis, shift exposure experiment, and data analysis. At the same time, with the help of the open source software GIMP and Fiji perform image processing to obtain panel gray data, the Mura degree was quantitavely evaluated. Then, the ratio of exposure Mura was decreased from above 10% to below 1% through adjusting the illumination uniformity of exposure equipment and controlling the optimal production path, effectively improving the panel display quality. Finally, the formation mechanism of exposure Mura was further elaborated based on ExpertLCD optical simulation data and capacitive coupling effect analysis. It is found that pixel CD should be controlled within a certain range and good uniformity. If the pixel CD is too small or too large, the exposure Mura will be easier to appear. Meanwhile. The CD of each conductive layer also needs to ensure good uniformity to reduce the effect of coupling capacitance on the display.