Abstract: This paper presents a single-stage single-phase buck boost photovoltaic inverter which can suppress common mode current the inverter is obtained by cascading H-bridge inverter with buck boost chopper circuit,reusing related components and simplifying the circuit. It can simultaneously achieve voltage up and down to adapt to the wide input range of DC side voltage,without electrolytic capacitor application,and has the ability to effectively suppress leakage current,ensuring the reliability and safety of the system,It is very suitable for small and medium power photovoltaic system. In addition,a nonlinear modulation strategy based on modulation wave reconstruction can significantly reduce the size of the DC side energy storage inductor,effectively improve the power density,and achieve balanced voltage up and down. The working principle is described in detail,and the common mode analysis shows that it can effectively suppress the leakage current of the anode and cathode,and realize the balanced voltage up and down control under the new modulation strategy. Based on the theoretical analysis,the simulation and experiment of grid connected inverter control are completed,and the results are consistent with the theoretical analysis.