Element-scale specimens of cemented soil piles were designed to investigate the mechanical characteristics of the cemented soil-soil interface with different curing ages （i.e.7， 14， 28， 35 and 60 days）. The complete curve of shear stress-displacement at the interface between cemented soil piles and soil was measured at different ages. Based on the element-scale test results， a hyperbolic evolution model was proposed to describe the development of interfacial peak shear strength and residual shear strength. Besides， to obtain the variation of compressive strength and shear strength indicators （i.e. cohesion， c and internal friction angle， φ） of cemented soil piles with curing age， uniaxial and triaxial compression tests of cemented soil samples under the same curing ages， as well as the triaxial compression tests of soil were carried out， respectively. The results showed that there was a linear relationship between the shear strength of the cemented soil-soil interface and the compressive strength of cemented soil. At last， the constitutive model of the cemented soil-soil interface of the specimen comprising curing age was established according to the experimental results and the disturbed state concept theory. The model fits well with the measured data， which provides a reliable calculation model for the theoretical analysis and numerical simulation in cemented soil pile engineering.