The paper proposes a novel three-phase Z-source ac-ac converter topology, presents its circuit configuration, operating principle and control method. The proposed ac-ac converter employs a unique LC network to suppress the over-current and surge voltage due to the shoot-through or the open-circuit of the two switches. By controlling the duty cycle, the Z-source can provide buck-boost function, produce greater or less voltage than the line voltage. As a result, the new Z-source ac-ac converter reduces line harmonics, improves power factor and reliability. Analysis, simulation and experimental results are presented to demonstrate these new features.