To address the requirement for low power of a magnetically suspended flywheel, the energy optimization of permanent magnet-biased radial magnetic bearing is studied. The magnetic circuit and working principles are introduced, based on the current stiffness and displacement stiffness mathematical models of a magnetic bearing, and the energy optimization factor σ of a magnetic bearing is obtained. The objective function of the power consumption of the magnetic bearing is then established, followed by optimization of the consumption. Subsequently, a mathematical expression for optimal power consumption and the value of σ are determined. The power consumption of the magnetic bearing is simulated and verified using the finite element method. The obtained results are tallied with the results of the theoretical analysis. Finally, based on the results of the optimization, a magnetic bearing is developed and power consumption is tested to improve the existing 15-Nms magnetically suspended flywheel. The results show that when the amplitude is 10 μm, the value of optimal power consumption for each winding is 0.85 W, with a maximum error of 7% compared with the theoretical optimal power consumption of 0.79 W. The designed efficiency of a magnetic bearing consuming low power is improved using the energy optimization method, which is important for the power optimization of flywheel systems.