An electronic device monitoring system includes a server, a first electronic device, and a first power feature identifying device. The first electronic device is electrically connected to a grid. A first voltage and a first current are variable. The first power feature identifying device communicates with the server by a first communication protocol. The first power feature identifying device is disposed between the first electronic device and the grid. The first power feature identifying device extracts a plurality of voltage-time features, a plurality of current-time features, and a plurality of voltage-current features of the first electronic device in a first predetermined time, and the first power feature identifying device transmits those features to the server to generate a first power profile based thereon. The server monitors whether the first electronic device is in normal operation based on the first power profile.