Hardness and internal stress are very important in nickel electroforming. Nickel sulfamate bath has been widely used in electroforming because of its low internal stress and moderate hardness. Nickel sulfamate bath without chloride was chosen to investigated the effect of plating variable such as temperature, PH, current density and sodium naphthalene trisulfonate as addition agent on the hardness and internal stress. It was found that hardness increased with increasing temperature and decreasing current density and ranged from 150∼310 DPH. The hardness was highest at $55^{circ}C$ and 10∼40 mA/$ extrm{cm}^2$. The internal stress increased with increasing current density and decreasing temperature. It was minimum at PH 3.0∼3.8. Low internal stress within $pm$1,500 psi was obtained at both $50^{circ}C$ and $55^{circ}C$ in 10-20 mA/$ extrm{cm}^2$. The addition of sodium naphthalene trisulfonate was found to be effective in refine columnar grains thus resulted in decreasing internal stress, increasing hardness and improving brightness.