Abstract: The corrosion inhibition of brass by a low phosphonic copolymer in the artificial cooling water was investigated with weight loss measurements, energy-dispersion X-ray analysis(EDX) and electrochemical tests.The surface elemental compositions of the tested brass specimens without and with the copolymer inhibitor were analyzed, and the inhibition mechanism was studied.The results showed that the adsorption of the low phosphonic copolymer on the reactive sites of the brass specimen surface inhibited the anodic reaction.