Abstract: Under operating conditions, dissolved gas components in oil, grounding current of iron cores and clamps are effective methods to determine the operating status of transformers. In order to accurately determine the internal state of transformers when the dissolved gas components in oil and the grounding current data of iron cores and clamps are abnormal, as well as to more accurately locate and eliminate abnormal points after power outage, this article analyzes in detail the various possibilities of multiple grounding abnormalities and dissolved gas components in oil under two operation modes of two point grounding and one point grounding for iron cores and clamps, and proposes corresponding methods for judging and resolving abnormalities, Finally, experimental verification was conducted on a 110 kV abnormal transformer, indicating that the analysis has practical significance in determining and eliminating multi-point grounding problems, and has high application and promotion value.