The invention relates to the technical field of concrete, in particular to a concrete anti-crack self-repairing agent, a preparation method thereof and anti-crack self-repairing concrete. The concrete anti-crack self-repairing agent comprises, by weight, 35-80 parts of bulking fillers, 0.1-1 part of magnesium aluminum silicate thixotropic agents, 0.1-2 part of polyvinyl alcohol fibers, 1-3 parts of nano-scale black carbon, 2-5 parts of glucose and 3-8 parts of casein. The particle diameter of the nano-scale black carbon is 20-80nm. The anti-crack self-repairing agent is added into the concrete, the inside of a crack touching water is softened, expanded, remodeled and solidified under the action of the self-repairing agent when the surface of the concrete is cracked, so that the crack of the concrete is plugged and self-repaired, and the compressive strength of the concrete is improved. The anti-crack self-repairing agent can be mixed and stirred along with raw materials the concrete in processing and stirring process of the concrete, normal processing of the concrete cannot be affected, and the self-repairing agent is high in practicability.