The invention provides repair mortar. The repair mortar is prepared from the following components in percentage by mass: 5-15% of silicate cement, 30-50% of sulphate aluminium cement, 10-30% of doublequick cement, 1-2% of redispersible latex powder, 5-10% of expanding agent, 10-30% of silica sand, 0.1-0.5% of early strength agent, 0.5-1% of rheological agent, 0.2-0.5% of defoaming agent and 15-20% of water. According to the repair mortar, the multiple kinds of cement are adopted for compound use, by reasonably selecting the cement types, optimizing a ratio of the cement and adding the appropriate additives of the shrinkage-compensating material expanding agent, the early strength agent and the like, the finally obtained repair mortar has the advantages of fast setting, high early strength, high bonding force and no shrink; an example result shows that setting time of the repair mortar is about ten minutes, the strength in half an hour can reach 8 MPa or above, and the requirements offast repair and the durability of precast units are met.