The invention discloses a preparation method of an endogenous oily 
humectant for tobaccos. The preparation method comprises the steps of adding a 
solvent into a tobacco 
raw material, extracting by heating, carrying out suction 
filtration, concentrating filtrate to form paste, 
settling the paste by using 
ethanol, regulating the 
acid value by using NaHCO3 and 
hydrochloric acid, desalting, and carrying out static 
microwave vacuum drying on a 
sediment to obtain crude 
polysaccharide; primarily purifying the crude 
polysaccharide, and dialyzing to remove small-molecular impurities after separating and purifying by sequentially using a DEAE-
cellulose column, a SephadexG column and a Sephrose column to obtain pure tobacco endogenous 
polysaccharide; adding a 
solvent into the tobacco 
raw material to carry out cold extraction, carrying out suction 
filtration, concentrating filtrate until no 
solvent is separated out, adding a solvent to dissolve, carrying out suction 
filtration, and removing the solvent to obtain tobacco oil substances; and dissolving the pure tobacco endogenous polysaccharide by using a solvent to obtain a solution with the 
mass concentration of 50%, then, mixing the solution and the tobacco oil substances to 100 parts according to the 
mass part of (1-99):(1-99), homogenizing at 
high pressure, and uniformly mixing to obtain the endogenous oily 
humectant for tobaccos. After the 
humectant is added into 
cut tobaccos, the smoking quality of cigarettes can be ensured, and the 
moisture retention and 
moisture-proof effects are remarkable.