The aufhors calculate and analyze the arcing grounding overvoltage of 10 kV power network in case of neutral ungrounded and grounding through nonlinear resistance using EMTP, with a actual 10 kV power network of a substation in Guizhou province as an example. The emulational calculation results show that the grounding method which grounds through nonlinear resisitance has the advantages of the other two methods, can better limit the arcing grounding overvoltage and can not stop the power supply .even one phase is grounded by fault, so it can ensure the security of the power networkg supply . the network neutral grounding through nonlinear resistance needs more deep study and analysis as a new network neutral grounding mehtod.