A high-efficiency high step-up ratio direct current converter with an interleaved soft-switching mechanism is provided. The direct current converter includes a voltage-multiplier circuit and an active clamping circuit. The voltage-multiplier circuit includes two isolating transformers, two main switches disposed on a primary side of the two isolating transformers, four diodes disposed on a secondary side of the two isolating transformers and four capacitors disposed on the secondary side of two isolating transformers, configured to boost a voltage of a direct-current power to a desired voltage value. The active clamping circuit, electrically connected to the voltage-multiplier circuit, includes two active clamp switches and a clamp capacitor to lower a voltage surge of the two main switches so that the two main switches and the two active clamp switches can be soft switched on.