The invention discloses a preparation method of a dispersion antiwear boronation viscosity index improver. The preparation method comprises following steps: a ethylene-propylene copolymer dry rubber is introduced into a base oil for heating dissolving so as to obtain an ethylene-propylene copolymer rubber solution; maleic anhydride and a radical initiator are added into the ethylene-propylene copolymer rubber solution for grafting so as to obtain an acid anhydride rubber solution; the acid anhydride rubber solution and an organic solvent are mixed to be uniform, an amination agent is added foramination reaction so as to obtain an amidation viscosity index improver; the amidation viscosity index improver and an organic solvent are mixed to be uniform, and a boronizing agent and a catalystare added for boronizing so as to obtain the dispersion antiwear boronation viscosity index improver. When the dispersion antiwear boronation viscosity index improver is used in internal combustion engine oil, excellent thickening capacity and anti-shearing capacity are maintained, certain dispersion effect and wearing resistance are achieved, the dispersion and anti-wear additives in internal combustion engine oil are reduced, and excellent internal combustion engine oil dispersion capacity and anti-wear capacity are maintained at the same time.