The　mechanic　characteristics　of　sand　have　obvious　features　of　state　dependence,　which　is　mainly　reflected　by　the　fact　that　the　deformation　characteristics　of　sand　in　different　stress　and　density　states　significantly　differ.　The　reasonable　description　for　the　state-dependent　hardening　rule　and　dilatancy　rule　of　sand　is　the　basis　to　describe　the　state-dependent　deformation　characteristics　of　sand.　A　differential　expression　which　can　effectively　describe　the　isotropic　compression　and　critical　state　of　sand　is　proposed.　Based　on　the　hardening　rule　under　isotropic　compression　condition,　a　state-dependent　hardening　factor　ω　is　proposed,　and　the　state-dependent　hardening　parameter　H　is　developed　in　order　to　reasonably　decide　the　magnitude　of　plastic　strain　increment.　In　the　process　of　determining　the　direction　of　plastic　strain　increment　by　adopting　the　non-orthogonal　plastic　flow　rule,　the　influences　of　state　parameter　ψ　on　fractional　order　μ　are　introduced,　and　the　state　dependence　of　the　direction　of　plastic　strain　increment　is　considered,　thus　reasonably　describing　the　state-dependent　dilatancy　of　sand.　Furthermore,　by　introducing　the　state　parameter　into　the　Hooke’s　law,　the　elastic　strain　increment　is　obtained,　and　a　non-orthogonal　elastoplastic　constitutive　model　which　can　describe　the　state　dependence　of　sand　is　proposed.　By　reasonably　predicting　the　results　in　triaxial　drained　and　undrained　tests　on　the　Toyoura　sand,　it　is　proved　that　the　established　model　can　effectively　capture　the　state-dependent　mechanic　characteristics　of　sand.　©　2023　Chinese　Society　of　Civil　Engineering.　All　rights　reserved.