In the process of long-term production and old devices replacement, some typical problems continue to appear because of oven factor, such as ED particle with yellowish-brown color, yellow crust from topcoat oven and color values fluctuation for white color. Based on the working principle of hot-air oven, the causes of the above problems were analyzed, and targeted solutions were pointed out. The first, adjusting the temperature setting and using a special chemical agent to wipe ED oven could eliminate the ED particle with yellowish-brown color. The second, balancing hot air for each area and optimizing exhaust system of topcoat oven could cut down yellow crust effectively. The last, sealing leak point between abutting joint and matching PID parameters to the topcoat oven could make sure that the hue of white color would be in standard permission scope.