This　study　aims　to　develop　a　novel　Magneto-rheological　Fluid　(MRF)　elevator　traction　transmission　with　a　high-torque　capacity.　The　MRF　device　has　the　property　that　transmitting　torque　and　braking　torque　values　changes　quickly　in　response　to　an　external　magnetic　field　strength.　In　this　study,　the　fundamental　design　method　of　the　cylindrical　MR　traction　transmission　device　is　investigated　theoretically.　A　Bingham　model　is　used　to　characterize　the　constitutive　behavior　of　the　MRF　subject　to　an　external　magnetic　field　strength.　The　theoretical　method　is　developed　to　analyze　the　torque　transmitted　by　the　MR　fluid　within　the　design.　An　engineering　expression　for　the　torque　is　derived　to　provide　the　theoretical　foundation　in　the　design　of　the　coupler　and　brake.　Based　on　this　equation,　the　volume　and　thickness　of　the　annular　MRF　within　the　coupler　and　brake　is　yielded　after　algebraic　manipulation.　The　study　shows　the　design　of　the　MRF　traction　transmission　conforms　to　the　torque　requirements　for　elevator＇s　safety.　It　certifies　that　the　appropriateness　of　the　experimental　design　and　method,　the　analysis　and　interpretation　of　the　data　are　sufficiently.　©　2013　Asian　Network　for　Scientific　Information.