The invention discloses a high-efficiency flame retardant wood plastics composite. The high-efficiency flame retardant wood plastics composite is prepared from 50 to 75 weight parts of wood powder, 10 to 30 weight parts of plastic resin, 1 to 5 weight parts of interfacial compatibilizer, 0.5 to 2 parts of impact modifier, 1 to 3 weight parts of lubricant, 1 to 5 weight parts of other functional aid, and 10 to 30 weight parts of flame retardant. The preparation method comprises the following steps of: degreasing and drying wood powder, organically modifying bentonite and zinc borate and mechanically grinding, mixing in a high-speed mixing machine to obtain premix, and mixing and plasticizing in a double-roll plasticator and performing compression molding. The bentonite and the zinc borate which are treated organically and aluminum hydroxide are compounded to form a novel fire retardant, the mechanical property of the material is kept, the flame retardant effect of the wood plastics composite is improved and the using amount of the aluminum hydroxide is greatly reduced; and the bentonite and the zinc borate are organically ultrafined, the problem that an inorganic additive is not easily compatible with other components so as to influence the mechanical property of the composite is solved and the flame retardant requirement of the wood plastics composite is met.