A　hydro-mechanical　constitutive　model　for　unsaturated　soils　is　proposed　to　describe　the　hydraulic　and　mechanical　behaviour　over　a　wide　saturation　range.　Bishop＇s　effective　stress　and　the　effective　degree　of　saturation　are　taken　as　the　basic　constitutive　variables.　A　simple　and　novel　loading-collapse　yield　curve　is　constructed　to　capture　the　variation　of　the　yield　stress　with　the　hydraulic　state　over　a　wide　saturation　range.　A　non-orthogonal　plastic　flow　rule　is　adopted　to　obtain　the　direction　of　the　plastic　strain　increment.　A　simple　water　retention　model　is　developed　to　describe　the　hydraulic　behaviour　of　unsaturated　soils.　The　proposed　constitutive　relation　is　presented　through　the　calculation　of　the　total　strain　increment　and　the　calculation　of　the　increment　of　the　effective　degree　of　saturation.　All　material　parameters　can　be　determined　through　conventional　laboratory　tests.　The　performance　of　the　proposed　model　is　illustrated　through　numerical　examples　of　three　classical　stress　paths,　i.e.,　the　isotropic　compression　path　with　constant　suction,　the　wetting　path　with　constant　net　stress,　and　the　triaxial　shearing　path　with　constant　suction　and　mean　net　stress.　The　capability　of　the　proposed　model　to　capture　the　hydraulic　and　mechanical　behaviour　of　unsaturated　soils　is　validated　by　simulating　the　test　results　from　the　literature.　©　2023　Elsevier　Ltd