The invention discloses a flash extraction method for rabdosia rubescens polysaccharide and application of the method in cigarettes. Firstly, rabdosia rubescens is smashed into powder, water is added and mixed evenly, the obtained material is arranged in a flash extractor for extraction, an extracting solution is centrifuged to obtain liquid supernatant; flash concentration is carried out on the liquid supernatant, and ethyl alcohol is added into the concentrated solution to carry out treatment to obtain precipitate; the precipitate is dissolved by adding water, deproteinization is carried out on the obtained solution by adopting a Sevage method, the solution after deproteinization is concentrated, and the concentrated solution is dried to obtain rabdosia rubescens crude polysaccharide; the crude polysaccharide is separated and purified through DEAE-Celluose gel chromatographic columns and Sephadex G200 gel chromatographic columns to obtain refined rabdosia rubescens polysaccharide. High purity rabdosia rubescens polysaccharide can be obtained through the method, operation is simple, cost is low, and the extract time is short. Experiments show that when the extracted rabdosia rubescens polysaccharide is applied to the cigarettes as humectant, the irritation and miscellaneous odors of the cigarettes can be lowered, and the mellow and full feeling and the comfort ability of the cigarettes are improved.