Abstract: The security of human-robot interaction for a Stewart parallel manipulator is studied. Firstly, a static model of the manipulator is developed, the force sensitivity and force sensitive direction of joint are proposed to evaluate the perception of joints for operating force, and the analytical method and the numerical method are combined to calculate the global joint force sensitivity. Secondly, the distributions of joint force sensitivity in Cartesian workspace and orientation workspace are analyzed, and the influence of configuration parameters on the global and local force sensitivities is given. The security of human-robot interaction can be increased by improving the joint force sensitivity through some measures, such as constraining the workspace, adjusting the position and orientation at work, and choosing feasible configuration parameters at the design stage. Finally, experimental tests show that the joint force sensitivity is an effective index for evaluating the joint sensitivity for interaction forces, and the changes of position and orientation of the end effector can affect joint force sensitivity directly.