The effect of magnet pole design on the magnetic field distribution in a magnet gap for a magnetic fluid-based separator was analyzed by simulation, using a finite element software package for magnet design, and the results were compared to measured values. Good agreement was obtained between the simulated and experimental values. The effective densities of the magnetic fluid within the separation zone were modeled by combining magnetic field gradient values and fluid magnetization data. These results also compared well with the observed values. Moreover, the results confirmed the existence of density gradients within the separation zone. Simulation studies were used to demonstrate that non-uniformity in the effective density of the magnetic fluid could be reduced by magnet shape modification.