Abstract: To investigate the transportation mechanism of chloride ion in manufactured sand concrete（MSC）, the chlorine salt erosion tests under dry-wet cycle were carried out under the conditions of different sand replacement rate, fly ash content and stone powder content. The mass fraction of free chloride ions and diffusion coefficient of chloride ions in concrete were obtained by the experiments. The results show that with the increasing of manufactured sand（MS） replacement, the chloride concentration at the same concrete depth and chloride diffusion coefficient of concrete is decreased with latter increasing. The concrete with 50% manufactured sand has the highest resistance performance to chloride ion penetration. With the increasing of fly ash content, the chloride penetration resistance of manufactured sand concrete is increased with latter decreasing. The manufactured sand concrete with 30% fly ash can resist the chloride penetration with the best effect. Compared with the MS without or containing 11.6% stone powder, the chloride ion erosion resistance of concrete with 5.8% stone power is the strongest. Proper amount of manufactured sand in concrete can improve the durability life of concrete in the dry-wet cycle of chloride solution.