Tandem skew rolling process is a new process for producing seamless steel tubes,which combines the piercing and the rolling in traditional production of seamless steel tube and rolls the billet into the tube by the method of continuous skew rolling directly. The process implements continuous rolling, such as piercing and rolling extension, piercing and secondary perforation and multi-channel skew rolling deformation. Aiming at the particularity of tandem skew rolling process,the method of stream function is adopted to establish the deformation model in the process. The velocity fields are obtained under the boundary conditions of the velocity as well as constant volume conditions, which is the basis of plastic deformation theory for solving the strain rate,deformation power,process parameters. Tandem Skew Rolling testing mill is developed and the corresponding process experiments are carried out. It is proved that the process is feasible and the accuracy of the mathematical model,which establish the groundwork for the further production application.