Using　the　ring　shear　apparatus,　the　variation　rules　of　residual　strength　of　17　saturated　claysoil　samples　with　different　plasticity　indices　under　different　consolidation　conditions　are　studied.　The　influences　of　current　normal　stress,　over-consolidation　ratio,　plastic　index　and　multistage　shear　mode　on　the　residual　strength　are　analyzed.　The　variation　of　shear　strength　index　with　different　plasticity　indices　under　large　deformation　and　the　corresponding　practical　formula　are　investigated.　The　test　results　show　that　with　the　increase　of　the　current　normal　stress,　the　residual　strength　increases.　The　over-consolidation　ratio　does　not　have　a　significant　impact　on　the　residual　strength.　With　the　increase　of　the　plasticity　index,　the　residual　strength　reduces　gradually.　Under　the　small　stress　level　the　residual　strength　is　nonlinear.　Under　large　deformation,　the　residual　internal　friction　angle　increases　while　the　plasticity　index　decreases.　Finally,　the　formula　for　the　relation　between　the　residual　internal　friction　angle　and　the　plasticity　index　is　proposed.　©　2017,　Editorial　Office　of　Chinese　Journal　of　Geotechnical　Engineering.　All　right　reserved.