Abstract: To fulfill the microgravity level of scientific experiment payloads in space lab, vibration isolation performance of platform with experiment payloads is required. And the actuator of platform under control needs to produce active force timely to restrain the vibration of platform. This paper firstly presents the elementary parameters of actuator. Various structural forms are designed, based on the theory of magnetic suspension. Finite element simulations about magnetic circuit and coil design of the actuator are given based on various forms. To provide basis for the detailed design of actuator, the strong points and shortcomings of each form are concluded through comparisons. The parameters for comparisons mainly involve the mass, the air gap, the maximum force, the current density, the supply power, and the bandwidth of the actuator. The result of comparisons shows that each form is available due to different working conditions and system demands.