When electric vehicles (EVs) run on the wireless power supply coils, the multi-load working mode will appear, showing that that more than one EV is collecting energy from one coil. Aiming at the stability problem of multi-load mode, this paper mainly analyzes how the number of loads influences the system stability and defines the boundary condition of the load quantity. Meanwhile, an L-shaped coil structure and the T-shaped magnetic core structure are proposed to solve the problem of coil breakdown for high-power supply situations. The proposed structures effectively reduce the supply coils’ self-inductance on the premise of guaranteeing the power transfer, and ensure the security of the multi-load system. At last, the validity of theoretical analysis is verified by simulations and experiments.