Objective To assess the influence of replacing inhibitors on the anti-corrosion treatment of chilled water system. Methods This paper studied the changes of corrosion resistance of A106B and B10 in the replacement process from the original in-hibitor (NaNO2-Na2MoO4) to a new inhibitor (LiOH-N2H4) by the means of electrochemical tests and surface analysis methods, such as linear polarization and AC impedance tests, SEM and XRD. Results The electrochemical results showed that the Rp value and Rt value of two pipe materials increased gradually while the Icorr value decreased in the replacement process of inhibitors. The surface analysis results showed that there was little rust on metal surfaces in original inhibitor solution, the rust layers were formed during the replacement process of inhibitors, and the rust layers were not thickened in the new inhibitor solution. Conclusion The original NaNO2-Na2MoO4 medium had a good protective effect on the metal above by inhibiting anodic corrosion process. A106B carbon steel suffered a uniform corrosion and a rust layer formed on its surface, while B10 copper-nickel ally had a lesser degree of corrosion when the inhibitor was replacing, indicating the anti-corrosion property of the two materials was not decreased. The novel LiOH-N2 H4 medium, which can enhance the compactness of rust, was able to reduce the corrosion rate of rusted metal and increase the corrosion resistance of metals. It is feasible and operable to replace NaNO2 -Na2 MoO4 with LiOH-N2 H4 medium for the anti-cor-rosion treatment of chilled water system of nuclear power plant.