Abstract: A thermal-mechanical coupling model of a copper cooling stave with variable slag coating was founded based on thermal elastic mechanics, and the influence of the gas temperature, the cooling system, the materials of insert bricks, and the properties of the slag on the stave life and the stability of the adherent dross was analyzed from the view point of the stress distribution of the stave body and the slag-brick interface. The results show that the increase of the gas temperature linearly improves the stress of stave body and reduces the stability of the adherent dross meanwhile. The stress of the stave body and the stability of the adherent dross both decrease at first and then increase when the slag coating thickness increases, and the slag coating thickness should be controlled between 30 to 60 mm. The increase of water velocity incurs tiny growth of the stress of the stave body, while the stability of the adherent dross is enhanced. The stress of the stave body is weakly reduced with the increase of water temperature, but the stability of the adherent dross decreases heavily meanwhile. The increase of the heat conductivity of insert bricks and the decrease of the heat expansion coefficient of the slag significantly reduce the stress of the stave body and enhance the stability of the adherent dross.