This study established an electromagnetic-thermal bidirectional coupling model for the Domino magnetic coupling resonant wireless power transmission system, revealing the mechanism by which temperature rise affects system performance. Through the finite element and Simulink joint simulation platform, the loss calculation, thermal boundary conditions and temperature-resistance feedback mechanism are integrated to analyze the dynamic thermal accumulation law of the system. The temperature rise causes a significant increase in the resistance of the compensation board and the coil, forming a positive feedback loop of “current generating heat—resistance increasing—loss intensifying”. Bidirectional coupling simulation confirmed that the thermal effect significantly reduced the system’s output power and transmission efficiency, and the performance degradation was more obvious than that of the unidirectional model that ignored the thermal effect.