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.