Temperature crack in the pouring process of mass concrete of concrete arch dam and gravity dam could be a hidden troubles that affects the safety of the dam, especially reduces the tensile strength and shear mechanical properties of concrete dam, and also affects the long-term stability and the service life of the dam. During the pouring of mass concrete of a hydropower station, part of the dam was affected by temperature and cracks penetrated through. By using the crack grouting material for the hydropower station dam, we carried out indoor tests and compared the test results. The indoor tests include shear test on the original concrete core sample with no crack from the dam, shear test on cube concrete samples with cracks (made by splitting) and concrete core samples after simulation chemical grouting, and shear test on concrete core samples with cracks fully bonded after grouting. Results show that after chemical grouting treatment on the cracks, the shear parameter f ′ reaches the 83% of the original concrete, and c′ s the 68% of the original concrete. The result of indoor chemical grouting simulation is better, with f ′ equaling the level of original concrete, and c′ reaching above 85% of the original concrete. Chemical grouting is an effective measure to treat dam cracks and improve the shear strength and the impermeability of concrete. The research results provide reference for reasonable values of mechanical parameters of concrete after chemical grouting.