Pore　structure　of　cement　mortar　was　tested　by　mercury　intrusion　porosimetry　(MIP)　with　different　water-cement　ratio　at　different　age.　Fractal　model　based　on　thermodynamic　method　was　used　in　calculation　of　pore　surface　fractal　dimension　of　cement　mortar.　The　relationships　between　pore　surface　fractal　dimensions　and　porosity,　pore　surface　area,　average　pore　diameter,　median　pore　diameter　and　strength　of　mortar　were　studied.　The　results　indicate　that　pore　surface　fractal　dimension　which　is　calculated　by　fractal　model　based　on　thermodynamic　method　can　represent　the　complexity　of　pore　structure　very　well,　and　pore　surface　fractal　dimension　has　poor　correlation　with　porosity　but　good　correlation　with　pore　surface　area,　average　pore　diameter,　median　pore　diameter　and　strength.　As　pore　surface　fractal　dimension　increases,　average　pore　diameter　and　median　pore　diameter　of　cement　mortar　decrease,　and　pore　surface　area　and　strength　of　mortar　increase.　Thus,　pore　surface　fractal　dimension　that　is　calculated　by　fractal　model　based　on　thermodynamic　method　can　be　assumed　as　integrative　evaluation　index　for　evaluating　the　pore　structure　characteristic　of　cement　mortar,　and　it　has　good　correlation　with　mechanical　performance　of　cement　mortar.