This paper proposes a novel quadratic boost converter (QBC) based ultra-high gain DC-DC converter with coupled inductor (CI) and voltage multiplier cells (VMC). Based on the structure of this converter, the energy leaked through the coupled inductor can be recycled and transferred to the output to improve the voltage gain. Meanwhile, it has the common ground characteristics and good static output stability. The converter is tested for an application requiring the output power of 50W∼300W, operating with 25V input voltage and 547V output voltage, and it has the voltage gain of 21.8 under the medium and low duty cycle, the peak efficiency is 92.5%.