In order to simplify balancer’s self-locking structure, the magnetic balancer obtaining self-locking state by design of magnetic circuit is proposed. When coil is not energized, there is a minimum magnetic resistance between the adjacent two permanent magnets and magnetic toothed discs, so the stable balanced position can be held. When coil is energized, the balancer starts and then moves to the next stable position under the interaction of electromagnetic fields and permanent magnets. The structural parameters of balancer affecting its self-locking torque and starting torque are discussed, and these parameter’s ranges are roughly designed. By finite element electromagnetic analysis, the quantitative relationships between these parameters and self-locking torque and starting torque are obtained. Based on the above results, the design and development of magnetic balancer prototype are completed. Its self-locking reliability calculation and test, starting capability and stability test are accomplished. Compared with the results of calculation and test, the structural design and parameter selection of the developed balancer are correct. This work provides an important reference for the future engineering applications of the proposed balancer.