A low-cost direct metal RP process based on the plasma arc welding (PAW) is presented. The impacts of two important process parameters (pulse current and wire-feeding speed) on the distortion of the substrate are investigated. The temperature field and the distortion of the depositing process are simulated by finite element analysis. The results show that the heat input and the quantity of the metal fed into the molten pool influence the distortion of the substrate. Higher pulse current and wire-feeding speed will bring on larger distortion.