Abstract: Due to the structural and loading complexities, difficulties arise in the analysis of trunnion-knuckle bearing system of actuator. An equivalent model is developed to investigate the structural characteristics of the trunnion-knuckle bearing system of actuator. The interaction between inner ring and outer ring of knuckle bearings is identified as the key factor in the system analysis. With well lubrication, the tangential action of the inner-outer ring can be omitted and there is only compression action in normal direction. In this paper, a new link element model is presented to simulate inner-outer ring interaction under pure compressive condition. This model can avoid contact analysis of hyperbolic surfaces and element distortion, therefore the calculation convergence is assumed. With this model, the strength of trunnion-knuckle bearing system is analyzed, which is helpful to structural design.