A semi two-stage DC-AC power conversion system composed of a Boost DC/DC converter and a novel dual-input inverter is presented in this paper. The low voltage DC source and the output of the Boost DC/DC converter are used as the low-voltage and high-voltage DC input ports, respectively, of the dual-input inverter. So part of the input power can be supplied to the inverter directly and will not be processed by the front-end Boost converter. As a result, the conversion stage, power/current stresses of the Boost converter, and associated power losses are reduced, and the overall conversion efficiency is improved. In addition, the two input ports provide a multi-level voltage to the inverter, which will lower the voltage stresses and switching losses of the switching devices. A 1000W prototype is built and tested to verify effectiveness and advantages of the presented semi two-stage power conversion system.