Abstract: A method for preserving a fermentation broth of an engineered strain of D-psicose-3-epimerase includes: adding a lysozyme into a fermentation broth of an engineered strain of D-psicose-3-epimerase, stirring to make the OD600 of the fermentation broth less than or equal to 1 to obtain an enzyme solution; and adjusting the enzyme solution to be weakly alkaline with an alkali liquor, and storing the weakly alkaline enzyme solution at room temperature. According to the invention, the enzyme solution is obtained by adding the lysozyme after fermentation, and then adjusted to be weakly alkaline. The lysozyme can dissolve the engineered strain to release the enzyme, and can also inhibit the growth of microorganisms. The alkaline environment of the enzyme solution can further inhibit the growth of other microorganisms in the enzyme solution. Therefore, the storage life of the enzyme solution is prolonged while ensuring the enzyme activity.