Abstract: This article designs a power supply status monitoring system in order to verify the reliability of the active electronic current transformer's power supply switching and monitor its power supply status. It is proposed that analyzing the merged unit IEC61850-9-2LE message to obtain primary current and analyzing the merger unit TCP/IP protocol to get the laser power and photovoltaic cell output voltage . while using a high-power optical splitter to monitor the laser power output directly, thus enabling the active electronic current transformer power supply status monitoring according to its working principle. Through this monitoring system, a certain type of active electronic current transformer is energized state monitoring test verification, the monitoring data can display the current energy status in real time, and gives several common power supply failure alarms. Experiments show that the monitoring system can verify the reliability of power supply switching and realize the alarm of power supply status so as to improve the quality testing capability of active electronic current transformer.