This paper introduces a complete online monitoring and remote fault diagnosis system for electricity meters at gateways.The all-time state monitoring of the metering device is realized by collecting the signals of electricity meters at gateways, CT and PT secondary circuits in real time.The functions of distinguishing, recording and warning of abnormal events are realized by the abnormal event library.The voltage and current waveforms generated by various faults can be reproduced on the fault simulation platform in the laboratory to realize remote error testing.The system can comprehensively improve the level of operation and maintenance management of metering devices at gateways and ensure the safe and stable operation of metering equipment.