Abstract: During firing, a large amount of heat is transferred into the gun bore. Many heat-induced problems, such as erosion of the gun-bore surface and barrel overheating, significantly limit gun performance. Barrel cooling, including passive cooling and active cooling, is an effective approach to diminish these adverse thermal effects. Passive cooling technologies, such as chromium plating and wear-reducing additives, are adopted to reduce the thermal energy input by setting up a thermal barrier between the hot propellant gas and the steel of the barrel. Active cooling technologies, such as finned-barrel cooling and forced liquid/air cooling, reduce the temperature increment of each round fired by increasing the thermal dissipation rate. Finite element analysis (FEA) results have shown that active liquid cooling is effective in controlling the barrel temperature, thereby preventing barrel overheating and increasing barrel life.