Traditional resonant converters generally use Pulse Frequency Modulation (PFM), which can easily lead to a wide range of switching frequency changes in wide input and light load applications, resulting in serious electromagnetic interference, loss of soft switching characteristics, and low utilization of magnetic components. In response to the above issues, this article proposes an improved hybrid control strategy of combining input control with PFM for optimization. This control strategy is applied to Buck-Boost Quasi-Resonant Converter (QRC), and voltage regulation is achieved through frequency conversion control, which can avoid distortion of the output waveform when the switching frequency changes over a large range, and has strong practicality. The applied converter was designed in Continuous Conduction Mode (CCM) and full-wave mode, and finally simulated under the improved control strategy proposed in this paper, verifying the feasibility of the method.