Abstract: The piercing tools and the mill adjustment seriously affect the wall thickness homogeneity of the shell, while the analysis of the opening of the cone type piercing roll acts as the basis for calculating the adjustment parameters and designing tools for the large angle rotary piercing. Due to the complex three-dimensional spatial relationship of the deformation zone, it is rather difficult to find out the opening value of the rotary-rolling groove with conventional mathematical method. When adjusting the input variables in actual application, the calculation process is cumbersome, and the application of the said method is limited in practice. Based on the mathematic equation analysis of the roll opening, the VB software for the backend development is used to design an opening analysis software that is capable of analyzing the roll opening value at any position within the groove, providing a basis for rolling parameter adjustment and the tool design.