The　isothermal　absorption　properties　and　kinetic　model　of　Cr　(VI)　and　Cr　(III)　onto　ettringite　were　investigated　using　the　batch　adsorption　method.　IR　analysis　was　used　to　study　the　difference　and　mechanism　of　the　adsorption　of　chromium　ions　with　different　valence　states.　The　results　show　that　the　adsorption　of　Cr(III)　onto　ettringite　at　20　degrees　C　agrees　with　Langmuir＇s　isothermal　model.　The　ion　binding　stability　was　significantly　greater　than　that　of　Cr　(VI).　While　the　adsorption　of　Cr(VI)　onto　ettringite　agrees　with　Freundlich＇s　isothermal　model,　the　D-R　model　fits　the　adsorption　isotherms　of　two　types　of　valence　Cr　(R-2＞　O.994).　It　can　be　concluded　that　the　adsorption　of　Cr　(III)　onto　ettringite　is　mainly　by　chemical　adsorption　and　that　the　adsorption　of　Cr　(VI)　onto　ettringite　is　mainly　by　physical　adsorption.　Dynamic　model　fitting　and　model　parameter　analyses　show　that　the　adsorption　of　Cr　(III)　onto　ettringite　agrees　with　the　pseudo　second　order　kinetics　model　given　by　Lagergren.　The　formation　of　chemical　bonds　is　the　main　factor　causing　the　fast　adsorption.　Cr　(VI)　adsorption　is　mainly　dominated　by　liquid　film　diffusion,　and　the　adsorption　rate　is　much　slower　than　that　of　Cr　(III)　adsorption.