The utility model discloses an electric field monitoring system device, characterized by comprises monitoring center, monitoring host computer, relaying machine and monitoring extension. A transformer substation can place several monitoring extension and be used for monitoring electric field information, monitoring host computer is given with this signal transmission in the indoor monitoring extension signal of transfer to the relaying machine, extension communication can be monitored with the several to a relaying machine, monitoring host computer can monitor extension (or relaying machine) communication with the several, be used for showing in this transformer substation monitor information and to surveillance center's transmitter data, the monitoring center is used for receiving several transformer substation monitoring host sends's information, and show the information of receiving. This system can monitor and show the electric power facility's of transformer substation electric field strength value, can remind staff somewhere electric field strength unusual through the surveillance center simultaneously to in time locate power equipment to this and inspect, get rid of the potential safety hazard of this equipment early.