Tailor rolled blank(TRB)is a type of emerging material to produce lightweight vehicle parts.Transitional zone′s shape is an important parameter for tailor rolled blank.It not only affects mold design and the local carrying capacity of the stamping parts,but also determines the maximum value and variation characteristics of rolling force.How to get the best transitional zone′s shape is a key problem for production of tailor rolled blank.A double power function is put forward using for transitional curve,which is continuous and smooth at all connection points independent of its parameters,so the sudden change of mechanical parameters during rolling and forming process can be avoided.At the same time,the velocity formula and restriction for arbitrary transitional curve are derived to preset vertical velocity of the roller and judge whether the curve can be rolled successfully or not.Then,the finite element method(FEM)is used to verify the precision of velocity formula and study the mechanical characteristics of different curves.Finally,a method to obtain the optimal curve equation is put forward and verified. Tailor rolled blank (TRB) is a type of emerging material to produce lightweight vehicle parts. Transition zone’s shape is an important parameter for tailor rolled blank .It not only affects mold design and the local carrying capacity of the stamping parts, but also determines the maximum value and variation characteristics of rolling force. How to get the best transitional zone’s shape is a key problem for production of tailor rolled blank. A double power function is put forward using for transitional curve, which is continuous and smooth at all connection points independent of its parameters, so the sudden change of mechanical parameters during rolling and forming process can be avoided. At the same time, the velocity formula and restriction for arbitrary transitional curves are derived to preset vertical velocity of the roller and judgment whether the curve can be rolled successfully or not. Chen, the finite element method (FEM) is used to verify the precision of velocity formula and study the me chanical characteristics of different curves. Finally, a method to obtain the optimal curve equation is put forward and verified.