The utility model relates to a mining electric power monitoring system belongs to coal mine power supply technical field. The utility model discloses a monitor platform, switch I, control communication substation, protector unit, switch II and embedded industrial computer, switch II be the tie of switch I and monitor platform communication, and embedded industrial computer be protector unit and the control tie that the substation communicated of communicating, embedded industrial computer independent wheel askes the protector unit that connects under the control communication substation, forward the entering with ethernet to the data storage, the packing that obtain, monitor platform's instruction converts RS485 serial data transmission to by embedded industrial computer and carries out tothe protector unit in order to pass to the storage of embedded industrial computer under the IP datagram form. The utility model discloses having solved the transmission of low -speed RS485 serial communication effectively and having occupy high -speed bottleneck with ethernet transmission bandwidth, it communicates between monitoring host and the protector unit to make occupies the bandwidth with ethernet hardly.