The Ni-P-nanodiamond electroless composite plating adopting nanodiamond made dispersed acid liquid and the technology for Nanodiamond Electroless composite plating on steel plate was studied. The effect of plating factors on the properties of the coating was studied with orthogonal tests. The optimum formula of nanodiamond electroless composite plating was as follow: nanodiamond 3.0g/L, temperature 85°C，pH 4.5.Microstructure, corrosion resistance and wear resistance of coating were studied. The result show that The nanodiamond content of the composite coating can get weight 15.44%, and the cystiform microstructure is fine and the cohension between coating and base is good. The coefficient of friction of coating is about 0.8 time compared with that of pure Ni-P coating and its corrosion resistance was improved greatly due to the fine nanodiamond particle occupying in the little pit.