The spiral mark is one of the quality defects on the tube surface in cone-type rotary pericing process. In this paper, the numerical simulation study was carried out for cone-type rotary piercing process using rigid-plastic finite element method. From the simulation results, the axial load applied on piercing plug and mandrel bar were then obtained. Taking the elastic deformation of mandrel bar into consideration, the variation of plug location under axial load during pericing process and the non-homogeneous wall thickness were investigated. The formation mechanism of the spiral mark on the tube surface can be found in the obtained results.