The invention provides a reconstituted tobacco incombustible after being heated and a preparation method thereof. The preparation method comprises the steps that biological treatment is carried out ontobacco leaves under the action of microorganisms to obtain primary biological treatment tobacco leaves; the primary biological treatment tobacco leaves are mixed with licorice root to obtain a mixture; water extraction and concentration are carried out on the mixture, and a complex enzyme preparation is added for biological treatment to obtain a secondary biological treatment concentrated solution; the secondary biological treatment concentrated solution is mixed with a modifier for a Maillard reaction to obtain a coating material; the surfaces of reconstituted tobacco bases are coated withthe coating material and dried to obtain the reconstituted tobacco incombustible after being heated. By means of the preparation method, the tensile strength and bulk of the reconstituted tobacco incombustible after being heated can be improved, and the reconstituted tobacco is not likely to adhere; meanwhile, the wood offensive odor and other bad smells are basically eliminated, and the reconstituted tobacco has the smell of licorice root.