Aiming at the question which magnetic Staunton effects are usually ignored in derivation of mathematical model of single winding bearingless switched reluctance motors(SWBSRM), this paper builds a mathematical model considering the characteristic of magnetic saturation with the Maxwell stress tensor method and the magnetic equivalent circuits. According to a prototype, a finite-element simulation model is established. Simulation results show the validity and the superiority of the mathematical model, by comparing it with the FEM simulation and the mathematical model based on the virtual work method, which can provide theoretical basis for more accurate in the research of the motor operation characteristics analysis, optimum design and control strategy..