Abstract: Transformerless converter has higher transmission efficiency and lower cost, thus it has broad prospects for application in low-voltage AC/DC distribution networks. However, the problems of leakage current and low quality of power supply limit the application of transformerless converters. Therefore, we constructed a common-mode equivalent circuit, and improved the traditional four-leg converter to obtain a common-ground four-leg converter without leakage current. Then, we analyzed the mechanism of DC-side diode and fundamental-frequency common-mode fluctuations under the condition of unbalanced load, and proposed the multi-objective composite control strategy of common-ground four-leg topology. Finally, the dSPACE experimental platform was used for comparison and verification. The results show that the proposed common-ground four-leg topology and composite control strategy can effectively suppress the leakage current and keep the bipolar DC bus voltage stable, thus realizing the safe and stable operation of the low-voltage AC/DC distribution network. The results prove the effectiveness of the proposed strategy.