The impermeability of recycled fine aggregate concrete (RFAC) with different content of recycled fine aggregate (RFA) was tested according to the standard test method of ASTM C 1202.The moisture states of RFA were controlled at air-dried (AD), oven-dried (OD) and saturated surface-dried (SSD) states.Both the interfacial structure and the pore structure of RFAC was analyzed.Research results show that, for the same total water-cement ratio and the same content of RFA, with the increase of the moisture of RFA from oven-dried,air-dried, to saturated surface-dried states, the interracial transition region of RFAC became denser and the density and porosity of hardened cement paste (HCP) were improved, which result in the higher impermeability of RFAC.For the same moisture state, with the increase of RFA content, Both the interfacial transition region and the property of interface structure of RFAC becomes weaker.The density and porosity of HCP are decreasing, resulting in the lower impermeability of RFAC.