In this paper, 3D-FEM (Finite Element Method) analysis code "DEFORM 3D" was applied to the simulation of the RR forging. The analytical features of this software were triangular gimlet elements with four nodes and remeshing function. And it is a suitable technique of analysis for complex deformation like the RR forging. For estimating the deformation and load accurately, the analytical conditions such as temperature dependency of flow stress, temperature distribution of material and the volume decrement caused by the oxidation scale were considered. As results, it was found the numerical results such as the shape of throw, the positions of flash and underfill showed good agreement with these of measured.