In order to study the Cl− penetration depth in polypropylene fiber concrete with different volume, indoor artificial method was used to simulate dry-wet cycle, and the concentrations of AgNO 3 solution indicator on the Cl− concentration at the color change boundary of the specimens was investigated. The results indicated that the chloride penetration depth increased as the cycles of dry-wet was increased, adding 0.1% PPF into concrete have the prefect resistance of Cl− penetration, the corner has the largest Cl− penetration area.