The invention provides a preparation method of a protection and repair system for the surface of a concrete base, convenient construction is achieved, and a systematic concrete protection and repair system with high adhesive force and durability is provided. The preparation method comprises the steps that the protection and repair system comprises a primer layer, polyurethane mortar layer and a polyurethane weather-proof finish paint layer, wherein the primer layer, the polyurethane mortar layer and the polyurethane weather-proof finish paint layer cover the surface of the concrete base from inside to outside, and the primer layer is obtained by solidifying monoisocyanate-terminated polyurethane prepolymers and a catalyst; the preparation method of the primer layer comprises the steps thatpolyester polyols and first isocyanates are subjected to a thermostatic reaction for 2-3h, a first part of dihydromethyl propionic acid is added to continue the thermostatic reaction for 1.5-2.5h, when the content of isocyanato reaches 16%-23%, cooling is carried out, the catalyst is added, and discharging can be carried out after stirring for 15-20 minutes and standing; and the polyester polyolsare linear or branched polyester polyols, and the mass ratio of the first isocyanate to the polyester polyols is (2.2-4.6) : 1.