In order to improve the stability of laccase, the effects of three additives(glycerol, inositol and sorbitol)on the acid-base stability of laccase were studied, and the protection mechanism of the additives on laccase was analyzed by UV spectroscopy, fluorescence spectroscopy and circular dichroism. The results indicated that the protective effect of the additives on laccase was related to the type and concentration of the additives. When the concentration of inositol was 0.2 mol/L in buffer at pH = 3, the relative activity of laccase reached the maximum(125%). With increasing the concentration of glycerol or sorbitol, the relative activity of laccase increased gradually. When the concentration was 0.6 mol / L, glycerol increased the relative activity of laccase by 29%, and sorbitol increased the relative activity of laccase by 15%. The optimum pH range for laccase should be at pH = 2 to 5, and the use of additives could improve the acidity of laccase. Spectral analysis showed that these additives could form hydrogen bonds with laccase molecules in the solution, resulting in the improvement on the acid-base stability of laccase.