Abstract: A novel high-boost coupled inductor DC-DC converter is proposed to meet the requirement of high gain DC bus voltage gridconnection in photovoltaic power generation system. The high voltage boost capability of the converter is improved by double adjustment of the coupling inductor turn ratio and switch duty ratio. The active clamping circuit is used to clamp the voltage of the switching device,and the leakage inductance of the coupling inductor is used to absorb the instantaneous current pulse of the switching device,which can effectively reduce the switching loss and pulse impact of the switching device,and prolong the service life of the converter. The switching tube voltage stress is low,the duty cycle is small,the switching loss is small,which is beneficial to improve the efficiency of the converter. The working principle and specific modes of the converter are analyzed,and the stress and selection basis of each device are deduced. The theoretical correctness of the novel DC-DC converter with high boost coupling inductor is verified by simulation and experimental comparison.