Abstract: Indentation force of strip forging between parallel platens was solved by us ing transmitted,differential equation of force equilibrim and plane strain yield criterion. It was found that the results (with or without bulge) are in excellent agreement with those derived with upper-bound, slab and uniform plastic-deformation energy methods of solution. However, since transmitted equation is introduced, deriving process is simplified drastically and calculation formula is different from all other methods in the refference of this paper. Furthermore, the formula is also suitable to calculation of deformation force for strip forg lag with bulge.