Abstract: The structure and parameters of the magnetic fluid seals are optimized by means of numerical computations and experiments. The design principle of the permanent magnet is discussed. The relations of the seal pressure differential to the sealing gap, pole piece angle and width of single stage seals are discussed. And the influences of the seal stage number, the tooth width, the width height and the slot width of multi stage seals on the seal pressure differential are analyzed. The optimized values are obtained.