The Cl- transport law of coral aggregate concrete under the synergism of Mg²⁺ and SO42- erosion was studied， and the Cl- transportation model for coral aggregate concrete under the “wick action” was established. The results show that Cl- is transported both from the bottom to the up and from the surface layer to the center longitudinal of the semi-immersed concrete， and the Cl- in concrete exhibits a parabolic distribution. SO42- will accelerate the transfer of Cl- in concrete， while the addition of Mg²⁺will inhibit the transfer of Cl-， resulting in the concentration of Cl- at the same height and depth in concrete be smaller than that under the combined action of SO42- and Cl-. The calculated results of the chloride ion transport model for coral aggregate concrete under the “wick action” established in this paper are in good agreement with the measured results.