Salt solutions based on Na2SO4， NaCl， MgSO4 and their pairwise mixed salts were set up to conduct drying-wetting cycle tests on blue brick samples， and the effects of soluble salts in the drying-wetting cycles on the quality， surface hardness， elastic wave velocity and color difference of blue bricks were studied. The deterioration mechanism of blue bricks was analyzed from the perspectives of macroscopic， fine and microscopic multi-scale and mineral composition changes. The results show that the mass， wave velocity and hardness of the test all increase first and then decrease， and the hardness continues to decrease. The compressive strength and capillary water absorption rate are reduced to varying degrees. Na2SO4 causes serious damage to the surface layer and a certain depth of blue bricks. MgSO4 destroys the pores in the brick， resulting in small cracks， but it is difficult to damage the surface layer of blue bricks. In contrast， NaCl only weakly erodes the surface layer of the brick. The interaction between the mixed salts changes their location of crystallization， quantity， and solubility， then it results in different deterioration patterns. Compared with single salt， the deterioration characteristics in the mixed salt chamber are more consistent with the disease characteristics in the actual occurrence environment. The results of this research will provide a reference for the protection and restoration of related buildings of brick cultural heritage.