Abstract: By adding a rectifier diode and two high-frequency switches on the secondary side of two-transistor forward converter, an interleaved three-level forward converter with variable turns ratio was proposed in this paper. Besides the advantages of interleaved two-transistor forward converter, the range of input voltage is broadened by adjusting turns ratio. Meanwhile, the proposed converter has the merit that the output filter can be reduced, and the power density can be increased. Moreover, the operation principle of the proposed converter is clarified and the two-level and three-level operation modes are also compared. Then, a specific design method of the parameters is described. A 2000 W experimental prototype was built to verify the theoretical analysis and the feasibility of the proposed technique.