The structure of active radial magnetic bearing with 12 magnetic poles of E type is designed according to the technical index of the 10 kW·h energy storage flywheel to the supporting system. Firstly, the effect of the number of magnetic poles on the supporting performance was analyzed. Then the mathematical model of electromagnetic force of 12 magnetic pole radial magnetic bearings was established. Secondly, having designed for the structure of the radial magnetic bearing and got the detailed structural parameters. The magnetic field distributions under different control currents were analyzed by Maxwell ANSYS finite element analysis (FEA) software. Lastly, using the designed electromagnetic force testbed, the electromagnetic forces under different air gaps are measured and analyzed. The simulation and test analysis result prove the effectiveness and feasibility of the radial magnetic bearings structure.