The influence of surfactant CTAB (cetyl trimethyl ammonium bromide) on electrodeposited nickel layer has been investigated in this research. Our result shows that CTAB added in the electrolysis bath can effectively remove the hydrogen to obtain a smoother nickel layer. The effect of CTAB on the surface roughness is also significant. It may be ascribed to the adsorption of CTAB on the electrode surface which results in a hindering effect in the electrodeposition process. Increasing the concentration of CTAB, the grain size of nickel deposit was reduced and the microhardness of the nickel deposit was therefore improved. The hardness of the metal layer can be promoted to 450 Hv when 300 ppm CTAB is added.