Recycled coarse aggregate concrete and ordinary concrete specimens were prepared with the same mix proportion. The recycled coarse aggregate concrete was sliced and samples were taken at the age of 3, 7, 14, 28d, and then their interfacial microscopic structures were observed by SEM. The compressive strength of recycled coarse aggregate concrete and ordinary concrete specimens were tested under axial loading. The distribution of internal cracks in recycled coarse aggregate concrete was also analyzed. It is concluded that with the age increasing, each interfacial transition zone(ITZ) in recycled coarse aggregate concrete has a certain degree of development. The development of ITZ between natural coarse aggregate and new mortar is relatively slow. The development of ITZ between old and new mortar in recycled coarse aggregate is the best. And the ITZ between natural coarse aggregate and old mortar in recycled coarse aggregate originally exists with some cracks. Compressive strength of recycled coarse aggregate concrete is slightly higher than that of ordinary concrete at the age of 3d, and equal at the age of 7, 14, 28d. The internal cracks in recycled coarse aggregate concrete are mainly distributed in the ITZ between natural coarse aggregate and new mortar and the ITZ between natural coarse aggregate and old mortar.