Abstract: The high temperature combustion gas of gunpowders results in the decreased surface material strength of barrel decrease，the phase change and the melting during gun firing. This will accelerate the erosion，wear and cracking of barrel surface. Therefore，it is important to study the surface temperature and its gradientof barrel bore to explain the damage mechanism of barrel. A thermal-structure coupling dynamic model is established for 155 mm gun barrel，and the influence law of rifling edge chamfering and in-bore chromium plating on the surface temperature of barrel is simulated and analyzed. he simulated results are compared by the thickness of heat affected layer on the inner surface of barrel. The results show that the surface temperature of barrel decreases rapidly along the radial direction，forming a great temperature gradient. The temperature of the inner surface reaches 1 500 ℃，and the temperature at 190 μm exceeds 727 ℃，reaching the phase transition temperature. There is obvious heat accumulation at the edge of rifling，which makes the temperature at this point more than 300 ℃ higher than that on the surface of rifling. And the temperature at the edge of rifling decreases about 100 ℃ after chamfering. And the chrome plating in the bore can reduce the temperature of the substrate by about 400 ℃.

Key words: gun, surfacetemperatureofbarrelbore, temperaturegradient, chromeplatingofbarrelbore