This paper analyzes the principle and test method of the grounding resistance. According to the analysis and calculation of the lightning accidents, prove the relationship between counter attack lighting and the grounding resistance. We also describe the basic principle of grounding resistance test. Basic method and disadvantage of grounding resistance test are introduced. We focus on the composition, working principle and advantage of the grounding resistance tester without dismantling the tower lead line, and we introduce the situation of field test. Confirm the grounding resistance tester without dismantling the tower lead line is no need to disconnect the tower grounding download, and it has the advantages of time saving, labor saving, strong anti-interference ability and high in precision. The device applicable scope broaden, the substation power equipment ground resistance test, but also applicable to the overhead distribution lines, tower grounding resistance test.