The voltage gain range in the over-resonant region of CLLLC resonant converter under pulse frequency modulation (PFM) at light load is insufficient. Phase shift modulation (PSM) can only realize the buck function, and the load switching perturbation has a large impact on the output voltage. In response to the above problem this paper proposes a variable frequency and phase-shift control method that can freely switch the control mode according to the input voltage range to achieve a wide voltage range soft switching and output voltage stability. The system model is acquired by the extended descriptive function method and reduced to the second order. The second-order linear active disturbance rejection control (LADRC) strategy is introduced to reduce the impact of the load casting perturbation on the output voltage and improve the dynamic performance of the system. Finally, the correctness of the theoretical analysis and the effectiveness of the control strategy are verified by PLECS simulation.