Abstract: The four-switch Buck-Boost converter is characterized by simple structure, low in-phase output voltage and power switching tube voltage stress, and a constant-frequency zero-voltage switching control strategy for the four-switch Buck-Boost converter based on linear self-impedance control is proposed for the fact that it is usually in the hard-switching state when it operates in a wide voltage range. Firstly, a simplified real-time control algorithm is derived by performing pulse-width modulation and phase-shift control on the basis of the quadrilateral inductor current modulation method to obtain the zero-voltage switching constraints in different modes, so as to effectively reduce the effective value of the inductor current. Secondly, linear self-immunity control is introduced to optimize the duty cycle and phase shift angle of the switching tubes, so that the system can keep the output voltage constant when the input voltage jumps or the load changes abruptly, and achieve smooth switching in different modes. In addition, this scheme eliminates the need for auxiliary methods such as table lookup and linear interpolation, which the computation amount of the control system is effectively reduced. Finally, the correctness and feasibility of the proposed control strategy are verified by building an experimental prototype of a low-power four-switch Buck-Boost converter.