Objective To improve the corrosion resistance of electroless Ni-P coating. Methods Passivation treatment for corrosion inhibition was conducted with phytic acid, sodium silicate, ammonium molybdate and hydrogen peroxide on the electroless NiP coating prepared on the steel substrate. The variation of corrosion resistance was investigated by dropping test and filter paper method. The optimal compositions of passivation solution were obtained by orthogonal experiments. Results The results showed that the complex inhibitor solution composed of phytic acid, sodium silicate, ammonium molybdate and hydrogen peroxide had good corrosion resistance in nitric acid dropping test. The electrochemical test showed that the corrosion current density of the composite passivation coating decreased and the impedance values increased by more than one order of magnitude. Conclusion The synergistic effect among the components in the passivation solution was observed. The optimized compositions of passivation solution were 6 cg/L of phytic acid, 6 g/L of sodium silicate, 4 g/L of ammonium molybdate, and 30 mL/L of hydrogen peroxide.