[Objective] This paper proposes and designs an axial-flux discrete-modular counter-rotating dual-rotor synchronous generator (DM-AF-CRDRSG), aiming to achieve wide-band potential modulation and stable power generation under multi-pole-pair magnetic field coupling. [Methods] Firstly, the stator of the motor was designed with a rectangular iron core, 6-slot three-phase fractional-slot concentrated winding. The dual-rotor excitation (2/4 poles) was selectively coupled with the dominant component of the stator magnetomotive force. Then, a prototype test platform was built, and no-load and load tests were conducted, with the results compared to simulations. Next, 11 magnetically equivalent two-dimensional finite element models were constructed using Ansys Maxwell software, with tooth-slot ratios ranging from 1 to 3 in equal steps, and the voltage waveforms characteristics under different tooth-slot ratios were studied. Finally, the results of the Maxwell 2D models were superimposed and converted to the prototype model, and the induced voltage waveforms and harmonic spectrum characteristics of the simulation and experiment were compared and analyzed to verify the feasibility of the motor topology. [Results] The induced voltage waveforms from both the simulation and experiment exhibited good sinusoidal characteristics and were found to be basically consistent. Although the harmonic content in the simulation results was higher and the amplitude was slightly larger, the consistency between the two still verified the correctness and effectiveness of the DM-AF-CRDRSG structural design. [Conclusion] The DM-AF-CRDRSG designed in this paper exhibits excellent spatial potential modulation capability and stable power generation performance under wide-band magnetomotive force excitation.