[Purposes] In view of the increasingly prominent problems of steel corrosion and cracking in concrete under harsh environments and complex loads, the effect of mixing bentonite and polyvinyl alcohol (PVA) fiber on the compressive strength and chloride ion penetration resistance of concrete was investigated, so as to improve the durability of concrete under harsh conditions. [Methods] Compressive strength test and chloride ion penetration resistance test were carried out on 16 groups of bentonite-PVA fiber concrete with different mix proportions. The effects of curing age, bentonite substitution rate, and PVA fiber content on the compressive strength and chloride ion penetration resistance of concrete were analyzed. At the same time, the microstructure characteristics of concrete with different amounts of bentonite and PVA fiber were observed by the scanning electron microscope (SEM) technology. [Findings] Moderate amounts of bentonite and PVA fiber can improve the compressive strength and chloride ion penetration resistance of concrete. The optimal bentonite substitution rate is 5.0%, and the optimal volume fraction of PVA fiber is 1.2 kg/m3. [Conclusions] The adhesion of bentonite particles on the surface of PVA fiber increases the roughness of the fiber and enhances the bonding between the fiber and the concrete, which makes the internal structure of concrete more compact, thus significantly improving the mechanical properties of concrete. This study can provide a reference for concrete modification in actual engineering.