This article introduces the operating principle and structural characteristics of the electromechanical integrated toroidal drive system. For its inner and outer toroidal double-stator structure, the equivalent current method is applied to calculate its spatial magnetic field, which is produced by the sector cylindrical magnetic teeth and the helical variable cross-section magnetic beam. For the application of the equivalent current method in the modeling of the magnetic field, an effective correction method is proposed. The flux density calculation models for the main magnetic field in the inner and outer air gaps are established under the unified coordinate system, and the analytical expression of magnetic field distribution in spatial air gap is deduced. Finally, the feasibility of the mathematical analytical model is verified by comparing the analytical calculation results with the finite element simulation results. The influences of the main structural parameters on the distribution of the air gap magnetic field and the torque are analyzed, which lay a theoretical foundation for the optimal design of the electromechanical integrated toroidal drive system.