Aiming to address the difficulty of balancing wide voltage gain and high efficiency of LLC converter, a LCCLC high-efficiency wide gain multi-resonant DC-DC converter with frequency-variable magnetic inductance is proposed. By organically integrating the new excitation structure and notch filter structure, a novel multi-component resonant tank network is constructed. Wide gain adjustment is obtained with a narrow and limited frequency scope. It helps to achieve efficient operation. In addition, a detailed analysis of resonant frequency and voltage gain characteristics is conducted. And the effect of passive parameters on the voltage gain is revealed. On this basis, by combining characteristic parameters and using Matlab program to set boundary conditions for parameter design, the converter has achieved various beneficial effects such as wide output voltage and high efficiency. A 500W (375V input, 59.3V–38.5V output, 86kHz–120kHz frequency scope) prototype based on the LCCLC topology is built to verify the rationality of the theory. The maximum operating efficiency reaches to 97.74%.