The invention provides an insulating coating liquid for improving the cracks of a surface coating of oriented silicon steel, a preparation method for the insulating coating liquid, and an oriented silicon steel plate. The insulating coating liquid comprises the following components in parts by weight: 100 parts by weight of phosphate solution, 2-10 parts by weight of magnesium oxide or magnesium hydroxide, 10-20 parts by weight of chromic anhydride or chromate, 2-10 parts by weight of boric acid, 10-20 parts by weight of an organic solvent, 80-200 parts by weight of silica sol, 5-20 parts by weight of zirconium sol, 6-15 parts by weight of nano zinc oxide, 2-10 parts by weight of antimony pentoxide sol and 80-120 parts of water. According to the invention, the oxide combination of zirconium oxide, zinc oxide, antimony pentoxide and the like has small particle size, high affinity with the coating liquid components, and high dispersity in a coating solution system, and the coating liquidhas high stability; and when the coating is dried to form a film, the oxide combination can neutralize the brittleness of film formation of surface silica sol, fill gap parts of the coating, improvethe stability and toughness of the film formation of the surface coating, and then integrally improve the strength and toughness of the coating, eliminate microcosmic surface cracks, and improve the magnetic performance of the oriented silicon steel.