Disclosed is a high boost ratio DC converter, wherein the first and second switches are controlled by a control chip and the control chip controls the first and second switches in the following sequence: the first and second switches both conduct; the first switch conducts and the second switch is cut off; the first and second switches both conduct; the first switch is cut off and the second switch conducts thus making a first and second inductors and a first and second clamp capacitors charge to a first and second output capacitors. Then the first and second output capacitors discharge a load. Therefore, the load voltage output from the DC power supply will be boosted owing to the discharged load from the first and second output capacitors. The boost ratio is 4/(1−D).