The invention relates to a material capable of completely biodegrading, containing the following parts by weight:100 of polyester resin, 5-100 of polylactic resin and the multipolymer thereof, 10-80 of compounding converted starch, 10-60 of inorganic fillers and 0.1-0.9 of resin acceptor, wherein the polyester resin is at least one of polybutylene succinate resin, polybutylene adipate resin and the multipolymer thereof. The invention also provides a preparation method of the material. The material capable of completely biodegrading can combine the advantages of each component and has high intensity, modules, elongation at break and toughness, good heat resistance, and the like, thereby meeting the property requirements of a plurality of plastic products in the market and in particular products, such as non-returnable containers, mess kits, agricultural films, and the like, which cause serious white pollution, retaining the complete biodegradability of the material and reducing the production cost under the precondition of no influence on the property requirement.