Abstract: The conventional transformer-less PV grid- connected inverters can only operate in buck mode and have common mode leakage current problem. In order to solve the aforementioned problems, a transformer-less double-grounded buck-boost PV grid-connected inverter was proposed. The inverter had three operating modes in one grid cycle, i.e., Buck, Boost and Buck-boost. The hysteresis current control as adopted. Only one switch was operated in high frequency in each operating mode, so efficiency of the system could be improved. Operating principle, parameters design and stability analysis of the inverter were illustrated. A reasonable loss calculation method according to the characteristics of the topology under the hysteresis control was given. Finally, a 330W prototype verifies the theoretical analysis.