A new method to design the diameter of pass (Dx) was established according to the deformation characteristics of rolling and the properties of unidirectional tensile curve. The thickness of the cross-section and pass diameter were decreased, while the reduction of area increases with the process, but the increment decreases to compensate the insufficient of plasticity decreasing caused by metal hardening.The design results show that the relative deformation gradually decreases along the rolling direction, which can make full use of metal plasticity.  The rolling force almost unchangeds during rolling, and the maximum force is located in the middle part, which is convenient to rolling deformation.