Abstract: We analysed the change trend and failure mechanism of the strength of concrete-cement soil interface considering the age effect by large-scale shear test. Combined with the results of cement shear test and unconfined compression test, the relationship between the strength of concrete cement soil interface, the shear strength of cement soil and the results of unconfined compression test was analysed qualitatively. The results show that the failure process of the concrete cement soil interface can be divided into three parts:(1) The formation of cracks in the concrete-cement soil interface; (2) The interface between cement soil and concrete begins to peel off; (3) The interface between cement soil and concrete is completely separated, and the two are in friction contact. The shear strength of concrete cement soil interface increases slowly in the early stage of curing, and increases rapidly in the middle and late stage. The unconfined compressive strength and shear strength of cement soil increase logarithmically with age, and have a positive correlation with the strength of concrete cement soil interface.