Abstract: The low leakage current and high efficiency are two key indexes for transformerless PV grid-connected inverters. The transformerless inverter has superior efficiency thanks to saving the transformer, but its switches work at the hard-switching state at present. This paper presents a new zero-voltage-transition H6 type transformerless PV grid- connected inverter. By introducing two resonant tanks into conventional H6 topology, the zero-voltage turn-on and turn-off for the high frequency main switches, the zero-current turn-on for the auxiliary switches, and the zero-voltage turn-on and turn-off for the freewheeling diodes are achieved. The operation principle, soft-switching conditions, duty cycle restrict, and resonant tank parameter design rule are analyzed in detail. Finally, the validity of the zero-voltage-transition full bridge inverter is verified by a universal prototype rated at 100 kHz, 1 kW.