Abstract: In order to quantitatively analyze the effect of slag components of self-shielded flux-cored wire on the slag detachability, the method of extreme vertex mixing regression and the Design Expert 8.0 software of stat-ease company were used to make experiment design and result analysis. In the experiment, the mathematic model of slagging rate and slag composition was established by using the seven components in the slag as the independent variables and the deslagging rate of the weld as the objective function. when the content of the four components is kept to be unvaried, the effect of the other three components on the dependent variable can be intuitively observed by two-dimensional contour map and the three-dimensional response surface diagram. The optimal slag composition was obtained by the function of optimization solution of the software. The experimental results show that the method has a good reference to the slag design of flux cored wire. The fitted equation to predict slag removal rate was similar to the actual slag removal rate by actual validation, which indicates that the method has some guiding significance for design of slag components of flux-cored wire.