A　series　of　drained　tests　of　ISO　medium　sand　were　performed　to　study　the　onset　and　formation　of　shear　band.　Using　the　digital　image　processing　technique,　the　multifunctional　triaxial　equipment　of　GDS　was　improved.　Strain　isogram　and　local　stress-strain　relation　at　every　sampling　time　point　were　recorded　based　on　the　improved　equipment.　The　onset　of　shear　band　was　from　inhomogeneity　of　soil,　while　the　inhomogeneous　deformation　can　be　induced　by　end　friction　and　initial　defect.　Based　on　results　of　global　stress-strain　and　local　stress-strain　relation,　the　end　friction　effect　was　found　to　have　a　strong　influence　on　the　radial　strain.　The　macroscopic　non-uniform　sample　was　obtained　by　putting　silt　clay　block　into　sand　sample,　evolution　of　shear　band　during　the　loading　process　showed　that　the　discontinuation　of　stiffness　formed　at　interface　of　two　materials,　with　inhomogeneous　deformation　developing,　macroscopic　continues　shear　band　fully　formed.　©　(2011)　Trans　Tech　Publications.