Ground microgravity simulation test plays an increasingly important role in guiding on-orbit service of the manipulator. However， the coupling dynamic characteristics of the manipulator and the microgravity simulator are acquired by the ground test. The existing microgravity simulation device， especially the air floatation method， has relatively high additional inertia， which leads to inaccuracy of the ground test results. In this paper， a novel magnetic air suspension microgravity simulation device is proposed. It consists of a magnetic steel plate， magnetic suspension air bearings， and slings. The magnetic suspension air bearings are suspended on the steel plate and dragged by the flexible slings to passively follow of the manipulator， thus reducing influences of the microgravity simulation device on the manipulator. Then， the multi-body dynamic models， corresponding to the system of a manipulator and magnetic air suspension microgravity devices， the system of a manipulator and air floating microgravity devices， and the system of the manipulator under zero gravity， are established and simulated to analyze the planar motion of the manipulator. Results confirm that the coupling dynamic influences of the magnetic air suspension microgravity device on the manipulator are greatly reduced compared to the air floating method. Furthermore， it is of great significance to improve motion smoothness and end positioning accuracy of the space manipulator using the proposed microgravity simulation experiments.