In order to obtain the maximum magnetic energy product in the sealing clearance of magnetofluid seal and
improve its critical pressure, a diverging stepped magnetofluid seal with small clearance was designed based on
the magnetic circuit design theory and the magnetofluid seal theory. Magnetic distribution and its theoretical
critical pressure were calculated by the finite element method, which could prove the reliability of design
method in the magnetic circuit. The paper studies the effects of axial clearance, radial clearance and pole tooth
number on the pressure capabilities of diverging stepped magnetofluid seal in specific values, which were analyzed
and compared in details. The results show that the magnetic flux leakage at the junction of the pole piece
and the permanent magnet in the diverging stepped magnetofluid seal leads the theoretical critical pressure calculated
by the magnetic circuit method to be lower than that calculated by the finite element method.
Moreover, when the pole tooth number in the axial clearance is not less than the pole tooth number in the
radial clearance, and the width of axial clearance is smaller than the height of radial clearance, the critical pressure
of diverging stepped magnetofluid seal is better than that of the ordinary magnetofluid seal.