Abstract: Based on an introduction of the basic concept,working principle and application classification of electronic current transformer,combined with the abnormal output of the neutral point electronic current transformer at the high voltage side of the main transformer in the 220 kV intelligent substation of Shanghai Power Grid,the troubleshooting and treatment process are analyzed in detail. The measures and precautions for defect treatment of electronic current transformer are put forward,so as to guide the operation and maintenance management of electronic transformer in intelligent substation.