To solve the problem of arc-suppression of single-phase grounding fault in neutral non-effectively grounded distribution network, an active arc-suppression method of grounding fault for distribution network based on secondary injection is proposed in this paper. By means of injecting current with power frequency into the neutral point of the network, the purpose of arc suppression of single-phase grounding fault can be achieved, which ensures the safe and stable operation of the power grid. The reference value of the injection current is obtained by injecting a specific current to the system twice. Injection current deviation signal is put into proportional resonant controller to drive inverter switch to generate inverter current. And then, the current is injected into the neutral point of grid through the filter circuit, which can suppress the fault voltage and current to zero. Simulation and 10 kV grounding fault experiments show that the method has fast response and high sensitivity, and can compensate the reactive current component, active current component and harmonic components of the grounding fault current, which realizes fast and reliable arc extinguishing of ground fault. This work is supported by Smart Grid Technology and Equipment Major Project in National Key Research and Development Program of China (No. 2016YFB0900600), Science and Technology Project of State Grid Corporation of China (No. 52094017000W and No. 52170217000S), and National Natural Science Foundation of China (No. 51425701 and No. 51737002) and Science and Technology Project of State Grid Hunan Electric Power Company Limited (No. 5216A01700AH).