The　test　of　soil　water　characteristic　curve　(SWCC)　and　its　mathematic　model　are　present.　The　SWCC　can　describe　the　relationship　between　unsaturated　soil　matric　suction　and　water　content.　Matric　suction　is　an　important　parameter　to　address　when　studying　the　engineering　properties　of　unsaturated　soil.　And　while　the　measurement　of　substrate　attraction　is　a　very　difficult　issue,　it　is　also　one　of　the　biggest　obstacles　in　the　engineering　applications　of　unsaturated　soil.　By　analyzing　and　researching　the　test　data　of　SWCC　researchers　can　initially　establish　the　mathematic　model　which　is　the　SWCC　equation.　The　Van　Genuchten　model　and　the　Fredlund　and　Xing　model　were　used　to　simulate　better　the　changes　between　the　volume　water　content　and　the　matric　suction.　Predictions　were　compared　with　experimental　results　to　determine　the　simulation　capability　of　the　model　for　the　soil　of　Beijing.