A　simple　numerical　simulation　method　is　proposed　to　investigate　the　mechanical　response　of　the　unsaturated　stratum　under　the　water　environmental　load.　The　proposed　numerical　simulation　method　applies　the　water　environmental　load　to　the　unsaturated　stratum　as　the　load　condition,　and　adopts　the　developed　non-orthogonal　elastoplastic　constitutive　model　for　unsaturated　soil　to　describe　the　mechanical　behaviors　at　the　material　scale.　The　mechanical　response　of　unsaturated　stratum　is　obtained　by　solving　the　discretized　governing　equation　of　the　mechanical　equilibrium.　The　proposed　numerical　simulation　method　is　implemented　based　on　the　commercial　finite　element　software　ABAQUS.　The　effectiveness　of　the　proposed　method　is　verified　through　the　element　tests　on　the　Botkin　silt,　the　element　tests　on　the　Pearl　clay,　and　a　model　test　of　the　rising　water　level　on　a　sand　column.　The　numerical　simulations　of　the　rising　and　decreasing　groundwater　level　in　the　unsaturated　stratum　are　con-ducted.　During　the　rising　groundwater　level,　the　non-collapsible　stratum　produces　rebound　deformation,　the　collapsible　stratum　below　the　groundwater　level　occurs　rebound　deformation,　and　the　collapsible　stratum　above　the　groundwater　level　mainly　produces　settlement　deformation.　During　the　decreasing　groundwater　level,　both　the　collapsible　stratum　and　the　non-collapsible　stratum　produce　the　settlement　deformation.