A novel high efficiency high step-up DC-DC converter is proposed in this paper. The proposed converter can achieve high voltage ratio with appropriate duty cycle by using the coupled-inductor and cascode technique. In order to achieve high efficiency, a capacitor is used to recycle the leakage energy of the coupled-inductor and reduce the voltage stress on the switch. Therefore, the low-voltage rating MOSFET with low conduction resistance can be used. The operational principles and steady-state analysis of the proposed converter are discussed in detail. Finally, a prototype circuit with input voltage 24 V, output voltage 200 V and output power 250 W is implemented to verify the performances of the proposed converter. The experimental results reveals that the highest efficiency of the proposed converter is 94.6%, the full load efficiency is 92.3%, and the 10% load efficiency is 93.8%.