When traditional robot joints are subjected to harsh working conditions such as high loads and strong impacts, the rigid drive method often leads to concentrated structural stress and unstable motion control, making it difficult to simultaneously meet the requirements of high output torque and environmental adaptability. This paper proposes a novel type of robot magneto-rheological compliant joint. This joint takes the magnetorheological damper as an important component of the transmission part and utilizes the rapid and reversible rheological property of the magnetorheological fluid to achieve the compliance of the joint. The joint is driven by a linear motor and features both high load capacity and high force control accuracy. Based on the structural design, a dynamic model of the joint was established. The results shows that this joint has a good response effect and could meet the basic requirements of being compliant. The research presented in this paper offers a novel approach for the development of innovative compliant robot joints.