In this work, the natural diffusion method and rapid chloride ion penetration method (RCM) are used to study the performance of polyaspartic aster (PAE) coating in marine structures protection. The ability of concrete resistance chloride ion permeability in marine environment is tested by such two methods. The results obtained by the two methods are compared, they agree well. The paper also study the change chloride ion permeability coefficient of marine concrete with different coating thickness and use scanning electron microscopy (SEM) to microscopic analysis. From microscopic research, only a few tiny holes appear in the sample section after 6 months corrosion. Compared with the samples without corrosion, the PAE coating still remains homogeneous and dense.