In this paper, an isolated soft-switching DC-DC converter topology with high-step-down conversion is proposed. Comparing with the conventional two-switch forward converter, it uses two series inductors L1 and L2 and a clamp capacitor C to achieve the lower output voltage and soft-switching operation. In order to prove above results, detailed steady-state analysis is presented, and an input voltage 380 V, output voltage 12 V, output current 75 A prototype converter was built. Finally, simulation results verify the theoretical analysis and show the significant advantages.