Abstract: Ethanolamine (ETA) has been selected as the pH control agent for the secondary loop water quality regulation in the third-generation nuclear power plant of China. Hence the determination and interference analysis of trace ETA in the secondary circuit is becoming one of the critical issues that have captured attentions. On the basis of a series of experiments it is discovered that these chromatographic columns (CS12A, CS16, CS18) can determine the concentration of ETA accurately without any other ions. Under the condition of simulated second-loop water quality in the nuclear power plant, the interference of Li⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺ and morpholine was mainly discussed when using CS18 analytical column to determine the concentration of ETA. The results showed that through the optimization of the chromatographic conditions, the concentration of trace ETA in the second-line water quality of nuclear power plants can be accurately measured with gradient elution when the column temperature is 50 °C, the inhibition current is 20 mA and the eluent flow rate is 0.36 mL/min.