A magnet stably suspending in magnetic fluid is influenced by several factors. The key to analyze prerequisites of suspension of immersed body in magnetic fluids is the establishment of an exact mathematical model. The magnetomechanical modeling of spherical magnet encased in spherical vessel is established. The influence on magnetic force by magnetic conductivity, remnant magnetism and radius of magnet, radius of container and off-centering of magnet is analyzed. The conclusion has universal character. The calculation results indicate that various parameters has inerratic influence to magnetic force, and the conditions for self-suspension always exist. The relation between various parameters and the self-supension position is discussed on the basis of analyzing features of suspension balance position, and methods of controlling self-suspension position are discussed.