The invention relates to a method to prepare flavor for cigarette by chemical degradation of beta carotene, which comprises the following steps: 1 weight portion of the beta carotene pure product is dispersed in 100 to 500 portions of dispersant; 10 to 50 portions of oxidant are added; heating in water bath is carried out, and the temperature is 70 to 90 DEG C; the heating in water bath reflows for 3 to 12 hours; and the obtained product is the flavor for degrading cigarette. The method uses the chemically-compounded beta carotene pure product to develop flavor for cigarette by chemical degradation; the production technology is simple and easy to control and the product change is small, which provides a practical and feasible technical proposal for preparing flavor for cigarette by degrading carotene. Compared with the prior art, the method has the following prominent advantages that: (1) the degradation product and degradation technology are convenient to control by using the chemically-compounded beta carotene pure product; (2) fragrant agent can be added directly by using ethanol as reaction medium to reduce the process procedure for preparing the flavor; (3) the use of anhydrous cupric sulfate as oxidation catalyst greatly improves the reaction efficiency; and (4) the production technology is simple with lower cost.