The　experimental　tests　of　Fujian　standard　sand　with　the　relative　density　of　30%　and　60%　were　performed　by　using　the　soil　static　and　dynamic　universal　triaxial　and　torsional　shear　apparatus　which　was　developed　in　Dalian　University　of　Technology.　A　series　of　drained　monotonic　shearing　tests　were　conducted　under　complex　stress　conditions　with　various　orientations　of　principal　stress,　constant　mean　principal　stress　and　coefficient　of　intermediate　principal　stress.　Based　on　the　comparative　experimental　results,　the　effects　of　orientation　of　principal　stresses　and　relative　density　on　shear　strength　as　well　as　volumetric　characteristics　were　respectively　investigated.　It　is　shown　that　the　drained　shear　behavior　of　sands　is　considerably　dependent　on　the　orientation　of　principal　stress.　Furthermore,　the　patterns　of　the　stress-strain　relationships　are　related　to　the　shear　stress　imposed　on　the　horizontal　and　vertical　planes.　It　is　indicated　that　the　relationship　between　generalized　deviator　stress　(or　the　effective　friction　angle)　and　orientation　of　principal　stress　in　phase-transformation　state　and　in　peak　state　can　be　represented　by　an　empirical　parabolic　model.　Finally,　the　influence　of　density　on　shear　behavior　is　also　discussed.　Compared　with　medium-density　sand,　the　shear-contraction　phenomenon　of　loose　sand　is　significant,　and　the　peak　resistant-shear　strength　decreases.