In order to improve the performance of dc-dc converter circuit in renewable energy power generation system, and overcome the problems of input current discontinuity and high inrush current in traditional Y-source converter, an improved Y-source dc-dc boost converter topology is presented in this paper. The voltage gain formula is derived by analyzing the topology and operating principle of the converter circuit. The proposed circuit topology inherits all the benefits of the existing Y-source converter and has several more advantages, including the higher voltage gain, continuous input current and small inrush current. The simulation and the experiments based on the prototype are performed. And the simulation and experimental results verify the rationality and superiority of the circuit topology.