Abstract: In order to solve the problems of low conversion ratio and high voltage stress of traditional Boost converter, a new single switch novel high conversion ratio DC-DC converter topology is proposed. The converter adopts non-isolation form, which can effectively reduce the loss of magnetic energy caused by leakage inductance in boost mode such as transformer or coupling inductance, and improve the power transfer ratio. The working principle of the proposed converter is analyzed in detail, and the transformation ratio equation based on the steady-state model is deduced. The experimental results show that the converter has the characteristics of high conversion ratio, low switching voltage stress and continuous input current. It is especially suitable for the grid-connected applications of new energy inverters such as fuel cells and solar cells.