In order to ensure the reliability and accuracy of electronic transformer in actual long running period, this paper proposes an online monitoring and calibration system for electronic transformer based on IEC61850. The program integrates the function of online monitoring into the acquisition device of electronic transformer, and realizes the real-time states collection and transmission of electronic transformer. Meanwhile, it designs electronic transformer online calibration device, sets up electronic transformer online calibration system architecture, and realizes the real-time accuracy calibration of electronic transformer. The monitoring system and calibration system are combined into a compositive system, which communicates with substation monitoring system based on IEC61850 standard protocol. The whole system reaches a comprehensive real-time detection of electronic transformer. Experiment shows that the system satisfies the requirement of accuracy of 0.05 class, and practical application of this system has achieved good results.