Aiming at the magnetic path structure, the electromagnetic field was analyzed by the ANSYS FEM. The magnetic field distribution of the MR fluids dampers of different structural models was analyzed. The response under the same excitation between the single class magnetic circuit and double class magnetic circuit was studied. And the configurations of the MR fluids dampers pistons that influence the electromagnetic field distribution were also analyzed. It could be utilized as a reference in designing the performances of MR fluids dampers.