The invention belongs to the field of building materials and particularly relates to a self-repairing functional additive for concrete and a preparation method of the functional additive. The functional additive is prepared by mixing the following raw materials in parts by weight: 40-60 parts of a polybasic ion complexing agent, 40-50 parts of calcium hydrogen phosohate and 1-5 parts of water-absorbent resin. The functional additive has the advantages of strong self-repairing capacity, good self-repairing effect on wide fissures, high repairing speed and the like, does not has a delayed coagulation effect, is relatively strong in practicability and has relatively strong application and promotion values in the self-repairing field of concrete.