Abstract: Thebearing capacity and the stiffness of radial magnetic bearings was studied by usingthe equivalent charges of magnetism,overcoming two drawbacks of previous research : a magneticring was taken as an unlimitedly long magnetic bar and the bearing force of magnetic bearings couldonly be estimated. The calculation of bearing capacity is formulated in this paper. The experimentsfor checking the formualus of calculating bearing capacity showed that the calculated results are wellconsistent with the measured results,the studies on the relations of bearing capacity and geometricalparameters of magnetic bearings by calculation have shown that the stiffness of radial magneticbearings is constant within the range of working conditions of magnetic bearings. Based on this,thestiffness parameter of magnetic bearings was put forward to obtain practical methods for designingmagnetic bearings. Finally,It is found that the relative displacements along axial directionsignificantly affect bearing capacity. So the attention should be paid to this aspect when thestructure of magnetic bearings is designed.