Abstract: According to the characteristics of CARR, the weight loss measurement was used to calculate the corrosion rate. This method combined the static test and dynamic simulation associated with the analysis of the factors for carbon steel corrosion, and the ion concentration ratios of Cl^-, SO^2-₄, Mg²⁺ and Ca²⁺ and the pH value as well as the content of corrosion inhibitor LJ-301 were mainly studied. The results show that in the secondary loop of CARR, the water quality is at the best state when Cl^-, SO^2-₄, Mg²⁺ and Ca²⁺ concentration ratios are 2.3, pH value range is 8.0-8.5, and the concentration of corrosion inhibitor LJ-301 is about 0.12 g/L. The anti-corrosion effect of 20# carbon steel is obvious after 24 hours soak or water impingement.