Abstract: This paper analyzes the risk of excessive gas content in transformer (reactor) insulation oil. This paper introduces an abnormal situation that the air content of insulating oil of 1000 kV reactor exceeds the standard and the gas can not be discharged all the time in the treatment process. Since the transformer manufacturer generally purchases the conservator and does not conduct thorough inspection and test on the conservator, the equipment quality cannot be guaranteed. In view of this phenomenon, the treatment scheme of excessive gas content is put forward. After inspection and treatment, vacuum oil injection and hot oil circulation shall be adopted for degassing treatment. It provides a reference for the defect treatment of transformer equipment in the future.