Weakly connected microgrid lacks terrestrial grid support, resulting in unstable system power flow dynamics and low fault current levels, and leads to complicate protection design. To address this, virtual leakage current is constructed using node voltage information to reveal the characteristics of line-end node virtual leakage current under normal disturbances, internal fault and external fault conditions. Based on this, a fault section detection criterion and fault distance calculation model are established, a fault detection and location method suitable for weakly connected microgrid is proposed. Finally, simulation results demonstrate that the proposed method accurately identifies faulted lines and phases under varying fault resistances, locations, and types, with fault location errors between main grid lines and microgrids interconnected lines remaining below 5 %.