C30　grade　concrete　was　prepared　to　produce　the　recycled　aggregate　with　different　mix　proportion　to　replace　natural　aggregate　in　concrete.　The　properties　of　recycled　aggregate,　the　properties　and　pore　structure　of　recycled　concrete　were　investigated.　The　results　show　that　the　recycled　aggregate　has　relatively　lower　quality　than　natural　aggregate,　consequently　the　recycled　concrete　has　low　slump　and　low　compressive　strength.　However　the　recycled　concrete　has　almost　the　same　quality　as　control　concrete　if　the　replacement　ratio　of　recycled　aggregate　is　under　40%.　The　recycled　aggregate　has　no　remarkable　effect　on　percentage　of　pores　with　a　diameter　larger　than　10　μm　in　concrete,　but　makes　the　capillary　and　gel　pores　increase.