In this research work, a self-sealing component for rotary shaft of a MR fluid based devices such as MR brakes and MR clutches is designed and tested by both simulation and experiment. The sealing component is composed of a permanent magnet and a magnetic core placed on a rotary shaft to replace a traditional lip-seal. After an overview of development of MR fluid based rotary devices and researches relating to MR fluid based sealing, a configuration of a self-sealing component for rotary shaft of a MR fluid based devices is proposed. The design and modeling of the sealing component is then conducted based on Bingham plastic rheological model of the MR fluid and finite element analysis. Based on finite element analysis, optimal design of the sealing component is obtained. Prototypes of the sealing component are then manufactured and experimental works are then conducted. Base on experimental results, performance characteristics of the sealing component are investigated and compared with simulated results.