Abstract: To study the dynamic coupling between the active branches of parallel manipulator in joint space, a dynamic model of general parallel manipulator in joint space is established firstly, and a dynamic coupling strength coefficient is defined based on the analysis of dynamic coupling moment. The coefficient with a unified scale is suitable for describing the dynamic coupling characteristics of general parallel manipulators. Secondly, the dynamic coupling strength coefficient is applied to analyzing the dynamic coupling characteristics of a 2(3HUS+S) parallel manipulator, and the variation law of dynamic coupling characteristics along the desired motion trajectory is obtained. The actual dynamic coupling moments of the active branches are measured in experiments, which verify the effectiveness of the theoretical studies. Finally, variation of the dynamic coupling strength coefficient along with the structural parameters is calculated for the 2(3HUS+S) parallel manipulator. In order to reduce the dynamic coupling between the active branches, the length of the joint lever and the ratio of the radius of the moving platform to the radius of the base platform should be reduced properly.