Abstract: Based on the transportation mechanism of chloride diffusion and mass conservation theorem in any finite control volumes of concrete,two dimensional differential diffusion equations are derived as discrete equations using Finite Volume Method (FVM). The FVM can be used to perform numerical simulation of chloride ion penetration into concrete and life prediction of concrete structural members with rectangular and circular section exposed to marine environment. According to the results of numerical simulation,the influence of exposure conditions and material composition on the chloride content and service life of concrete members with different section shape is studied. The results indicates that the exposure conditions and material composition have great influence on the durability of marine concrete,while the degree of influence is related to the geometric section shape,and the geometric shape effect is pretty obvious. Because the boundary condition of circular section is similar to that of one dimensional shape,the chloride content in circular section is less than that in rectangular section,and the service life of concrete members with circular section is longer than that with rectangular section. However,the difference between the two geometric shapes varies significantly in different exposure conditions and material composition. And the most remarkable difference can be found in the atmospheric zone and adding slag as admixture.