Hardened　concrete　is　a　porous　heterogeneous　material.　In　this　paper,　pore　structure　of　hardened　concrete　is　determined　by　mercury　intrusion　and　vacuum　saturated　absorption,　the　feasibility　of　these　two　methods　is　analyzed,　and　the　linear　correlation　between　the　results　detected　by　these　two　methods　is　created.　Effects　of　curing　ages,　water　cement　ratio,　and　air-entraining　agent　on　the　porosity　and　pore　size　distribution　of　hardened　concrete　are　analyzed.　The　results　show　that:　1)　porosity　measured　by　mercury　intrusion　can　be　converted　into　the　results　detected　by　vacuum　saturated　absorption　with　more　than　90%　accuracy.　2)　porosity　decreases　as　the　curing　age　increases,　and　the　proportion　of　large　aperture　and　total　pore　volume　also　gradually　reduces.