During the continuous launching of gun, the temperature of inside wall of gun bore increases substantially, which will cause a high security risk when the temperature exceeds the ignition point of all combustible cartridge. An application and device of infrared thermal imaging technology in gun bore temperature measurement was introduced, included the composition and temperature measurement principle of the device. Combined the course of replacing ammunition during the continuous launching process, the image processing techniques such as edge detection, contour extraction, and identification judgment were used in the gun bore temperature measurement device, it could automatically analyze the effective time and the target area of temperature measurement. Based on the resolving curve calibrated by least-square method, the maximum temperature and average temperature of the target area could be determined, and the device reported the temperature data to the gun control system in real time for it to determine whether to replace ammunition or strike, which could effectively improve the safety of gun during the continuous launching process.