A novel three-level buck-boost type inverter is proposed in this paper. It combines the series-parallel diode-capacitor network with the traditional buck-boost converter, plus the full bridge inverter as the back stage. The new inverter can boost or lower the input voltage. The operation principle of the inverter is investigated, theoretical waveforms are shown, relevant formulas are deducted. The control strategy is also designed in this paper. The results of the simulation indicate that the new inverter has the advantage of simple structure and high efficiency transformation.