A　comparative　experimental　study　on　monotonic　shear　and　cyclic　torsion　shear　behaviors　of　standard　loose　sand　under　the　same　stress　condition　is　carried　out　by　using　the　soil　static-dynamic　universal　triaxial　and　torsional　shear　apparatus.　The　correlation　between　static　and　dynamic　characteristics　of　saturated　sand　under　the　same　initial　consolidation　stress　is　investigated.　The　result　shows　that　the　strain　softening　and　hardening　characteristics　of　stress-strain　relation　is　closely　related　to　flow-slide　deformation　and　cyclic　flow　characteristic.　Although　the　strain　softening　characteristic　appears　under　both　loading　mode,　the　increase　of　deviatoric　stress　ratio　exhibits　hardening　characteristic　in　both　cases,　even　the　variation　modes　are　approximately　the　same.　It　extents　the　plasto-elastic　model　for　static　stress　condition　to　dynamic　condition　and　provides　the　physics　basis　of　establishing　the　constitutive　model　for　describing　the　stress-strain　characteristics　of　sand　under　dynamic　loading.