Magnetic fluid is ferromagnetic material in liquid state, so the surface configuration of magnetic fluid affects the magnetic field, and vice versa. To analyze the devices with magnetic fluid, the magnetic field equations and hydrodynamic equation should be solved simultaneously. This paper presents the numerical algorithm to obtain the surface configuration of fluid under the influence of gravity, pressure and magnetic field without conventional sim¬plified assumption. The algorithm consists of nonlinear finite element method and ferro-hydrodynamics, such as Poisson equations and Bernoulli equations, respectively The simulated configurations of fluid are compared with experimental results, and the influence of the amount of fluid and pole piece shape on the seal capacities are analyzed.