Abstract: To investigate the marine corrosion behavior of the CuPCr alloy steel with different microstructures, the bainite and ferrite plus pearlite structures were prepared after hot rolling at different cooling rates to provide specimens for fully immersed marine corrosion tests in which the corrosion was accelerated. The corrosion rate was determined by weight loss measurement. SEM, XRD and electrochemical characterization were used to evaluate the corrosion behaviors. The testing results showed that the bainitic structure can form compact corrosion layer on its surface in a shorter time, of which the corrosion resistance is obviously higher than ferrite plus pearlite structure. The uniform distribution of carbon in bainite decreases the number of microcells in substrate, thus reducing the corrosion current density of the steel.