Abstract: Most self-service terminals use laser printers as the tool for internal printing. When paper absorbs a lot of air and moisture due to long-term use or improper storage, the equipment failure rate significantly increases, such as internal paper jamming, paper bending, etc., which would lead to inability to complete the whole process, poor users experience, and other problems. Regarding these issues, a solution of installing a timed and temperature controlled heating module inside the printer is introduced in this article. Focusing on analyzing the abnormal printing of paper in humid weather, the internal modification and optimization of the printer is conducted; and the result verifies the effectiveness of the moisture-proof and anti roll device in optimizing the printing of paper in humid weather, thereby improving the overall stability of equipment operation.