Used for reference the transmission principle of few teeth difference planetary gear for reference, it is presented the drive principle with coupled magnetic-field and tow concrete structures of eccentric magnetic gear pair with few poles difference. Based on the nature that opposite rare-earth magnetic poles attract each other, this mechanism transforms the revolution inputted in eccentric planetary rotor into the outputted rotation of the planetary rotor, with the result that realizing the high torque of few poles difference magnetic gears transferred variably without mechanical contact and friction. It is analyzed the structure with axial and radial coupled magnetic-field in the method of equivalent magnetic path, brought in the magnetic-field coupling coefficient of permanent magnetic poles to simplify the analysis and operation, and gotten the related dynamic behaviors of the new type of magnetic gear. According to theoretical analysis, a set of 110 N•m speed reducer used for the industry, is manufactured. And the results, obtained from the experiments on the prototype, proved the correctness of the results analyzed by the theory of magnetic-field.