The　experimental　tests　of　Fujian　standard　sand　with　relative　density　of　30%　are　performed　by　using　soil　static　and　dynamic　universal　triaxial　and　torsional　shear　apparatus.　A　series　of　stress-controlled　drained　monotonic　shear　tests　are　conducted　under　complex　stress　conditions　with　constant　mean　principal　stress.　The　coefficient　of　intermediate　principal　stress　and　orientation　of　principal　stress　are　varied　so　that　their　coupled　influences　on　shear　behaviors　of　saturated　sand　are　explored.　Based　on　the　comparative　experimental　results,　under　the　same　initial　condition,　coefficient　of　intermediate　principal　stress　influences　the　stress-strain　relationship　of　saturated　sand,　but　does　not　make　obvious　effect　on　volumetric　strain　features.　It　is　shown　that　the　drained　shear　behaviors　of　sand　are　not　dependant　on　consolidation　stress　ratio　and　considerably　depend　on　coefficient　of　intermediate　principal　stress　as　well　as　orientation　of　principal　stress.　Furthermore,　both　coefficients　of　intermediate　principal　stress　and　orientation　of　principal　stress　affect　friction　angles　at　phase-transformation　state(PTS)　and　at　peak　state.　Finally,　introducing　a　factor　for　weighing　the　influence　of　orientation　of　principal　stress,　and　combining　with　the　test　results,　an　expression　for　strength　indices　taking　coupled　effect　of　coefficient　of　intermediate　principal　stress　and　orientation　of　principal　stress　into　account　is　obtained　by　using　generalized　twinshear　stress　criterion.