Abstract: This paper proposed a capacitor-diode（CD） cell construction method in which diodes were connected in a forward direction, and a series of CD structures were deduced by supplementing capacitors and short-circuit lines at different branches of the CD unit. The internal working principle is similar, but the voltage of the capacitor changes due to the transformation of the capacitor’s position. Combining the CD unit with the two-phase interleaved Boost structure, a series of high gain DC converters for low-power photovoltaic power system were further derived. Taking the optimal 4 CD high gain topology with the lower capacitors’ voltage as an example, the working process of the converter was analyzed in detail at first. Secondly, the specific expressions of voltage gain, input-output current, voltage and current stress of the switches were derived. Thirdly, the loss analysis of circuit was given. Finally, a 380 W experiment prototype was built to verify the effectiveness of the topology.