The　triaxial　equipment　of　GDS　with　digital　image　processing　technique　is　used　in　drained　test　of　sand.　The　result　shows　that　the　end　restraint　and　initial　defect　have　significant　effect　on　mechanical　properties　of　sand　sample.　End　restraint　and　initial　defect　of　sample　both　can　cause　inhomogeneous　deformation,　then　form　macroscopic　shear　band　in　soil　testing　and　numerical　simulation.　Shape　multiformity　and　formation　mechanism　of　shear　band　in　normal　consolidated　soil　is　analyzed　based　on　Modified　Cam-Clay　Model　under　plane　strain　condition.　The　result　shows　that　end　restraint　and　initial　defect　can　induce　and　control　the　formation　and　shape　of　shear　band.　The　impaction　of　different　boundaries　and　initial　defect　setting　are　analyzed.