In order to improve the gain of Cuk converter and reduce the voltage stress of switching tube and diode, the switching capacitor structure and coupling inductor voltage doubling structure were combined into the traditional quadratic Cuk converter to form a high gain coupling inductor quadratic Cuk converter. The diode-capacitance structure of the output end of the converter is not only a part of the Cuk structure, but also a passive clamp branch circuit of the switch tube S, which absorbs the leakage energy and reduces the voltage stress of the switch tube. At the same time, the working principle of the converter in continuous on-off mode is analyzed in detail, and the performance parameters are listed. Finally, the simulation verification in PSIM software proves the correctness of the theoretical analysis.