To address the issue of reduced growth activity of common microorganisms in low-temperature environments, which leads to a decrease in their ability to repair concrete, the healing effects of mesophilic and cold-resistant bacteria and their combination on the prefabricated crack in mortar specimen were investigated through injection method and quantitatively evaluated by comparing the flexural and compressive strength of mortar specimens before and after healing. The results show that the healing effect of microorganism on mortar cracks is related to its growth activity at different temperatures. Compared with Sporosarcina pasteuri fwzy14, which can only grow well at room temperature, the cold-resistant Brevibacterium frigoritolerans A779 has the capacity of growing at both room and low temperature, and therefore shows more balanced repairing ability. In addition, A779 can metabolize through both aerobic respiration and nitrate reduction with calcium nitrate as precursor, which enables it to grow inside the crack that is anoxic and repair the crack in depth.