Abstract: Under the effects of sulfate erosion and freezethaw cycles,the concrete of photovoltaic bracket foundations in the northwest saline soil area deteriorates rapidly. This article presents interface durability tests the on cement mortarconcrete,studying the changes in durability indicators under different erosion effects,establishing a damage degree based on the loss rate of interface shear strength,and analyzing the microstructure of the specimens using scanning electron microscopy.The results show that the damage to the specimen is the most severe under alternating action,followed by salt freezing cycle and finally dry wet cycle. The damage caused by alternating action on the specimen is a superimposition effect,with a damage degree 6.43% higher than that of a single erosion superposition result. Compared to MgSO4 solution, Na2SO4solution causes more severe interface degradation,with damage levels of 95.24%（Na2SO4）and 82.41%（MgSO4）after 6 cycles of alternating action. Microscopic experiments show that after undergoing alternating effects,the bonding interface of the specimen expands and widens, and erosion products are generated.