The　state-dependent　deformation　behavior　of　sand　is　reinterpreted　from　the　perspective　of　strain　increment　magnitude　and　direction　by　analyzing　the　existing　test　data.　A　state-dependent　non-orthogonal　elastoplastic　constitutive　model　for　sand　is　established　by　incorporating　the　state　variable　into　plastic　strain　increment　magnitude　and　direction,　respectively.　For　the　magnitude　of　plastic　strain　increment,　an　S-type　isotropic　compression　hardening　rule　applicable　in　large　stress　ranges　is　proposed,　which　is　extended　into　a　new　hardening　parameter　for　general　stress　states.　Furthermore,　the　state　variable　is　introduced　into　the　newly　proposed　hardening　parameter　to　consider　the　state　dependence.　On　the　other　hand,　the　non-orthogonal　plastic　flow　rule　is　employed　to　determine　the　plastic　strain　increment　direction.　To　consider　its　state　dependence,　the　relationship　between　the　state　variable　and　the　parameter　controlling　the　plastic　flow　direction　is　established.　The　comparison　with　the　test　results　of　four　types　of　sand　demonstrates　that　the　proposed　model　can　reasonably　capture　the　state-dependent　deformation　behaviors　of　plastic　strain　increment　magnitude　and　direction　of　sand.　©　2023　Elsevier　Ltd