Abstract: In pursuit of the "carbon neutrality and carbon peak" target, distributed generation(DG) is continuously connecting to traditional distribution networks, leading to a complex and diversified characteristic in the structure and flow of the distribution network. The monolithic radial power supply network is gradually evolving into a multi-source power supply network, with power flows and directions becoming increasingly unpredictable. Therefore, studying the impact of DG on the characteristic current of single-phase ground fault is of reference value and engineering significance in improving small currents grounding selection technology, enhancing selection accuracy, and enhancing the reliability of power supply grid. This study established a single-phase ground fault simulation model for neutral-point grounded systems with a reactor, and researched the impact rule of the characteristic current of grounding selection for single-phase ground faults when DGs are connected through non-grounded transformer branches to the system. Research has shown that the addition of DGs can increase the current in a single-phase ground fault, with the amplification effect being dependent on both the location of the fault point and the relative position of the small power source.