In order to study the repair effect of bacterial mineralization on concrete cracks, this paper uses recycled coarse aggregates as carriers to immobilize Bacillus subtilis, and then externally coats them with metakaolin-based geopolymer. The water absorption rate and cumulative water absorption gradient of the carriers are studied. Moreover, calcium lactate is added as an organic calcium source for microbial mineralization. Recycled coarse aggregate concrete specimens with cracks are fabricated. Through tests such as surface observation, capillary water absorption, and chloride ion penetration, the repair effects of the carrier wrapping methods and the dosage of calcium lactate on concrete cracks are investigated. It is thus concluded that different aggregate wrapping methods affect the water absorption of aggregates, which indirectly influences the repair effect of concrete cracks; the compressive strength is linearly negatively correlated with the initial water absorption rate of concrete; as the dosage of calcium lactate increases, the cumulative water absorption gradient of the specimens first increases and then levels off.