Abstract: The definitions of welding pose parameters of arc welding robot were discussed.Welding pose includes weld position and torch orientation,which is represented by weld slope,weld rotation,torch work angle and traveling angle.The meanings of four parameters were amended,so that they are more compatible to the real nedas of arc welding robot,and easier to understand.The mathematical model of typical saddle-shape weld was established,and the welding pose parameters were calculated with MATLAB.