Abstract: An electrode coating slag system CaO-CaF₂- BaO-TiO₂-SiO₂ has been designed base on analyzing several domestic and abroad basic slag systems. The experiments were done with uniform design method and computer aided analysis. Nine to eleven coating components were taken as independent variables and they were divided into five levels in all twenty nine experiments. The AC arc stability was taken as target function and data were analyzed with mathmatical statistic software. The results given the influencing trend figures of coating components on AC arc stability and multinomial mathematical model between independent variables and function. With these trend figures and mathematical model the improving direction of electrode for AC arc stability can be inquired and be searched target optimization.