An electronic tag system and a method of updating electronic tag information are provided. The electronic tag system includes: a communication device, configured to receive updated annual inspection information; a display device, configured to display the updated annual inspection information; and a power control device, connected to the communication device and the display device respectively and configured to: connect, when the communication device receives the updated annual inspection information, a power source to the display device electrically to power the display device, so as to perform updating of annual inspection information on the display device; and disconnect the power source from the display device when the updating is over.