Abstract: The orbital energies and the charge densities of additive molecules 1,4-butanediol, 2 - butyne -1,4- diol, 2 - butene-1,4 - diol, nicotinamide, isonicotinamide and quinoline etc. for Ni electroplating were calculated with CNDO/2 method. It was found that there is a correlation between the frontier orbital energies of these molecules and there leveling property. The adsorption model and leveling mechanism were studied. According to orbital symmetry, the adsorptive bonding type of the additives on Ni surface was discussed. In addition, the molecules of oxalicacid and 1, 4 -butane diacid were calculated which are predicted to have good leveling and proved by experiments.