The invention belongs to the field of 
food preservation, and particularly relates to a fresh-keeping method for prolonging preservation duration of strawberries. The method comprises the following steps: selecting materials, preparing strawberry extracts, preparing a mixed 
chitosan solution, preparing fresh-keeping liquid, and soaking and 
air drying strawberries. The main components of the fresh-keeping liquid are supernate extracted from the strawberries and 
chitosan, raw materials of the supernate and the 
chitosan can be obtained conveniently, and particularly the supernate of the strawberries can be directly extracted from the bought strawberries, and is not required to be separately bought. According to the method, 
bacillus subtilis is added into the fresh-keeping liquid, so that growth and 
reproduction of mycete and 
botrytis cinerea can be effectively inhibited. Active substances, such as subtilin and gramicidin are produced during the growth of 
bacillus subtilis cells, and have obvious inhibition effects on the mycete and 
botrytis cinerea; in addition, the 
bacillus subtilis quickly consumes 
oxygen in the environment, and produces organic acids, such as 
lactic acid, so that the PH value of the environment is reduced, the growth of the mycete and 
botrytis cinerea is indirectly inhibited, and the storage duration is greatly prolonged.