The invention discloses a method for preparing an unsaturated polyester polyurethane block copolymer composite material. The method comprises the following steps of: gradually polycondensing dihydric alcohol, maleic anhydride and phthalic anhydride to form a hydroxyl-terminated unsaturated polyester oligomer; gradually performing addition polymerization on the unsaturated oligomer, diisocyanate and polyethylene glycol by using styrene as a solvent to form solution of an isocyanate-terminated unsaturated polyester polyurethane block prepolymer; blocking the prepolymer by using hydroxyethyl acrylate to obtain an unsaturated polyester polyurethane block active prepolymer system containing double bonds; and compounding the active prepolymer system and glass fiber under the action of a redox initiator and a curing accelerator to obtain the unsaturated polyester polyurethane composite material.