The invention discloses a preparation method of a high toughness polyvinyl chloride plastic. The preparation method comprises the following steps: burning and grinding clay, adding hydrochloric acid,allowing the mixture to stand still, filtering the mixture, washing, adding nano carbon, a plasticizer, and calcium lignosulfonate, keeping on stirring to obtained a prefabricated material (a); evenlystirring polyvinyl chloride, polyurethane rubber, octadecyl trimethyl ammonium bromide, mica powder, hollow glass bead, micro-encapsulated red phosphorus, and an antioxidant to obtain a prefabricatedmaterial (b); adding the prefabricated material (a) into the prefabricated material (b), keeping on stirring, extruding the mixture, cutting, and cooling. The preparation method has the advantages ofsimple operation, easily available raw materials, and low cost, the leakage of plasticizer is inhibited, and moreover, the obtained polyvinyl chloride plastic has the advantages of high density, goodtoughness, excellent performance on resisting impact and cracking, and resistance to rupture.