Abstract: The first man-machine cooperative test for in-orbit maintenance is conducted in China’s Tiangong-2 space laboratory. One task of the mission is to grab a floating ball by the space manipulator terminal. In order to investigate the characteristics of the relative movement between the space manipulator terminal and the floating ball, a physical and a mathematical model are established, respectively. Numerical simulations by the dynamic mesh method are carried out to study the movement of the floating ball under different conditions in the micro-gravity environment. The parameters for the floating balls are determined, as a basis for the systematic design of the space manipulator terminal. Finally, the simulation result is compared with the in-orbit test data, which verifies the method in this paper.