In this study, a high-efficiency topology-morphing multi-resonant DC–DC converter is proposed. The converter employs two auxiliary switches to control the equivalent resonant tank, and thus exhibits adaptive resonant characteristics for diverse situations. The dual-transformer MRC structure is applied when high-voltage gain is required, while a five-element MRC operates at the rated state for high-conversion efficiency. Besides, good protection for the over-current issue is guaranteed. Also, beneficial from the topology-morphing technology, the operating frequency range is very narrow and near every mode's high-efficiency region. Therefore, the proposed converter has an expanded voltage gain range and maintains high-efficiency throughout. These features make it well suitable for small-scale wind generation applications. Finally, a 500 W prototype is fabricated in the laboratory to test the performances. The input voltage varies from 80 to 600 V and the output voltage is constant at 400 V. The efficiency remains high (>96.5%) among the entire voltage gain range and the peak value reaches 97.93%.