Abstract: Confined by its own structure, three-element LLC resonant converter has the defect that the gain is sensitive to load changes, which facilitates the voltage regulation range and the conversion efficiency to be mutually restricted. Meanwhile, the power can only be transmitted through the fundamental wave. To solve the problems, this paper proposes a wide-gain DC converter based on the LLC-LC five-element resonant network, using a multi-mode voltage-multiplying rectifying unit and pulse width modulation method to obtain a wide gain range decoupling from the load; at the same time, the third harmonic power is transmitted by the five-element resonant network, which improves the efficiency of the converter. Finally, a PLECS simulation model and a 200 W experimental prototype are built, and simulation and experimental results verify the effectiveness of proposed five-element DC converter topology and its modulation method. The gain range is 1~4, and the conversion efficiency reaches 92.5%.