Abstract: Traditional bi-directional class E wireless power transfer circuits are prone to hard switching states, resulting in low power transfer efficiency. To solve this problem, this paper proposes an improved Class E^# circuit topology and its phase-shifting control strategy. Firstly, the mathematical model of the E^# circuit topology with a wider applicable load range for a zero-voltage switching state is designed. The key variables and constraints for the circuit to realize the zero-voltage switching state (ZVS) are analyzed and extracted, theoretically proving the effectiveness of the proposed topology. Then, the analytical relationships of the coil mutual inductance and load impedance in the circuit are derived. Based on this, a phase-shifting control strategy is proposed to guarantee that the system operates at the optimal states under different loads. By controlling the phase of the gate drive signal of the switching devices, the energy stored inside the resonant elements can be released in advance or with delay, thus correcting the switching devices back to a ZVS state. Finally, the effectiveness of the proposed bi-directional Class E^# circuit is verified via simulation and experiments. Numerical results demonstrate that the proposed method guarantees a circuit ZVS state within a load range of 5~30 Ω, and the peak power transfer efficiency reaches 84.3%.