The state-of-art of the related research for radial magnetic couplings was reviewed.A practical mathematical model and a novel criterion were set up.And then,improved Equivalent Magnetic Charge(EMC) method was compared with original one,Current Sheet Model(CSM) method and 3D FEA method in efficiency and accuracy.Finally,Design of Experiments(DOE) was introduced and an effective and practical optimizing process was proposed.The results show that the accuracy of improved EMC is increased by about 5% and the efficiency is increased by about 55% compared as that of the original EMC method.The error of the CSM method is big,though the efficiency of CSM is much higher.For the 3D FEA method,the circumstance is contrary.The proper initial values can be obtained only by using nine simulation models with the DOE method,and multiple sets of optimizing cases were obtained easily through standard optimization methods.The results show that proposed optimizing method can satisfy the requirements of practicability,higher precision as well as strong stabilization.