The mechanical and durability properties of nine groups of concrete， with various recycled coarse aggregate（RCA） replacement rates and water-to-cement ratios， were examined. Based on the experimental results and analysis， the length， volume and generalized interface parameters were determined； the correlation between three interface parameters and the RCA replacement rate， the water-to-cement ratio， the mechanical and durability properties were established. The results show that the mechanical and durability properties of RAC are closely related to the RCA replacement rate and the water-to-cement ratio； the generalized interface parameter reflects the effects of interface volume and water-to-cement ratio of new mortar on concrete properties， which reveals the degradation mechanism of RAC properties.