The invention relates to a preparation method of asparagus rough polysaccharide, including the following steps: a, asparagus is subject to prophase treatment and then is baked and smashed; b, water is added and extraction is carried out; c, separation, filtration and concentration are carried out; d, ethanol is added into concentrated solution, standing and filtering are carried out, and flocculent precipitate is dried, so as to obtain the asparagus rough polysaccharide. The asparagus rough polysaccharide is dissolved and then sprayed onto cigarette shred, cigarette smoke has no objectional odour, offensive taste and thrill are reduced, back to the sweet feeling and oral cavity comfort are improved, and entire smoking quality is improved. The invention does not change the original performance of cigarette, dose not change the original cigarette processing technology, overcomes the quality defects that cigarette moisturizing performance is poor, flue gas is dry and comfort is poor in national cigarette products and improves cigarette smoking quality, thus having significance and value of actual production.