Magnetic suspension flywheels are executing mechanism for spacecraft attitude control，which are supported by magnetic bearing. Based on the summary of the characteristics of magnetic bearing. this paper introduces the working principles of the laboratory model of magnetic suspension flywheel. and it also infers the dynamic equation of magnetic bearing. Besides，this paper introduces the calculating method the crucial parameters in designing magnetic bearing: axial unbalance stiffness，radial stiffness，angular stiffness. Lastly，the passive suspension characteristics of magnetic bearing are analyzed，active suspension control system is designed，and the results of the experiment are given. Some contents involved in this paper are of referential value for other devices supported by magnetic force.