Abstract: In order to study the tensile damage of 45 steel after dynamic corrosion in a simulated seawater environment, the corrosion reactor, acoustic emission detector (AE) and scanning electron microscope (SEM) were used to conduct the tensile mechanical performance tests on the corrosion samples, AE signal parameters, surface and fracture morphology of the corrosion sample during tensile process under the load were obtained. The results show that the relative energy of the generated AE signal during the tensile process of the specimen is mainly concentrated in the elastic stage, the yield stage and the strengthening stage; the number of AE signals is arranged in the order of strengthening stage> elastic stage> yield stage from big to small. As the load increases, the specimens begin to be damaged in the elastic phase, the damage is slightly reduced in the yield phase, and the damage in the early stage of the strengthening phase increases greatly; the tensile damage in the elastic phase is greater than that of the sample in the yield phase.The corrosion time affects the corrosion degree of the sample.The corrosion degree of the corrosion sample after 28 d is significantly greater than that of the corrosion sample after 14 d.A large amount of particulate corrosion is attached to the surface of the corrosion sample after 28 d.The damage in each stage of the corrosion sample after 14 d under load and tension is greater than that of the corrosion sample after 28 d.