Abstract: 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.