To　acquire　the　unscattered　transmission　of　the　bulk　bio-tissue　directly,　we　analyzed　the　spatial　distribution　of　the　transmitted　light　from　bulk　porcine　muscle　in　vitro,　and　carried　out　corresponding　experiments　under　irradiation　of　the　collimated　488　nm　Ar+　laser.　The　results　showed　that　when　the　sample　thickness　is　larger　than　3-4　mfp,　the　scattered　transmitted　light　is　isotropic　and　the　radiance　L(r,　t)　remains　constant.　The　difference　between　the　total　transmission　and　the　collimated　transmission　is　in　direct　ratio　to　the　square　of　sample-detector　distance.　The　unscattered　transmission　of　the　bulk　bio-tissue　can　be　obtained　by　shifting　the　detector　and　measuring　the　transmission　directly.　All　these　results　indicate　a　new　method　to　measure　the　optical　properties　of　bio-tissue.