This　paper　presents　a　new　model　for　describing　the　undrained　shear　behavior　of　reconstituted　clays　due　to　the　variation　of　initial　water　contents　based　on　the　concept　of　critical　state　soil　mechanics.　With　the　decrease　of　initial　water　contents,　the　reconstituted　clays　behave　enhanced　strength,　stiffness　and　dilation,　which　are　not　involved　in　the　Modified　Cam　Clay　model.　These　features　can　be　captured　by　introducing　a　new　hardening　parameter　(＇quasi-structure＇　strength)　into　the　conventional　critical　state　model.　The　＇quasi-structure＇　strength　increases　with　the　decrease　of　initial　water　contents.　The　available　test　data　on　the　undrained　shear　behavior　of　reconstituted　clays　at　different　initial　water　contents　are　used　to　verify　the　proposed　model,　and　the　comparisons　between　computed　and　measured　results　show　that　the　proposed　model　is　able　to　predict　the　overall　pattern　of　stress-strain　curves,　pore　pressure　variations　and　effective　stress　paths　reasonably　well,　especially　the　ultimate　undrained　strength　and　pore　pressure　response　at　large　strain.