The invention provides a novel high-strength repair mortar. After a formula is optimized, the high-strength repair mortar with high initial setting speed, high initial strength and high self-sealing performance is obtained. The mortar is prepared from, by mass, 300-350 parts of ordinary portland cement, 200-250 parts of sulphoaluminate cement, 50-100 parts of coarse whiting (calcium carbonate), 350 parts of river sand, 1-5 parts of a retarder, 0.5-1 part of fibers, 1-2 parts of hydroxypropyl methyl cellulose, 20-25 parts of rubber powder, 0.5-0.8 part of an organic silicon defoamer, 0.5-0.8 part of an early strength agent, 60-80 parts of gypsum and 220-280 parts of water. The raw materials are weighed, and are stirred for 5 min in a forced physical stirring mode to obtain the slurry-shapedrepairing mortar.