The invention relates to a composite tobacco aroma substance extracted by adopting a water extraction method and a supercritical CO2 extraction method. The composite tobacco aroma substance consists of a polar aroma substance directionally extracted from tobacco by the water extraction method and a nonpolar aroma substance directionally extracted from the tobacco by the supercritical CO2 extraction method, wherein the proportioning ratio of the polar aroma substance to the nonpolar aroma substance is 1000: (0.1-5). According to the composite tobacco aroma substance, the used tobacco raw materials are tobacco leaves, cut tobaccos or wastes, such as tobacco powder, tobacco ash or tobacco stems of tiny grains, generated during tobacco processing, so that the waste is changed into the valuable, and the pollution to the environment is reduced; a water extraction tobacco concentrate and a supercritical CO2 tobacco extract are mixed in an appropriate ratio, and a composite aroma material is sprayed to reconstituted tobacco, so that the quality of the reconstituted tobacco is improved, the aroma amount is increased, the aroma charm is improved, the natural tobacco aroma is set off, the smoke dryness is lowered, the smoke-induced saliva secretion feeling is enhanced, and the degree of comfort of cigarette is increased.