Transformer oil chromatogram test is an essential part of routine test, and its results can directly reflect whether there is a fault in the transformer. Taking the occurrence of acetylene component in oil chromatogram detection of 66kV transformer oil as an example, during the judgment of abnormal data, the phenomenon of arc discharge in the transformer is preliminarily judged by means of repeated test and DC resistance test, and the discharge trace left on the transformer is found and the discharge path is determined by further inspection of transformer disassembly, finally, the cause of the fault is obtained. At the same time, targeted repair schemes and preventive measures are formulated for the faulty transformer, and all factory tests are carried out again to verify the rationality and effectiveness of the conclusions and treatment measures.