Electric excitation synchronous motor has the advantages of no rare earth components and controllable excitation. These characteristics align well with the electric drive system's requirements for low cost and a wide speed regulation range. The traditional electric excitation synchronous motor requires brushes and collector rings to power the excitation winding, which hinder compact design and increase maintenance. A wireless excitation system with strong coupling capability and constant current output is proposed for axial flux electric excitation motor. Based on the magnetic field coupling wireless power transfer technology, a series-series resonant compensation topology is adopted to achieve constant current output. The coupling mechanism adopts a rotary transformer with an iron core structure to achieve high-coupling transmission. The windings use Litz wire to reduce high-frequency loss. Multi-parameter optimization design is applied for the coupling mechanism to meet the requirements of low loss and compactness. Finally, a simulation model of a multi-field coupled wireless excitation system is established. Under a 500 V DC voltage input, the excitation current is adjusted from 10 A to 60 A. The wireless excitation system achieved an efficiency exceeding 80%, with a peak efficiency of 95%. The simulation results prove the feasibility of the wireless excitation system for axial flux electric excitation motor based on wireless power transfer technology.