Considering to the joint temperature medium voltage power cable terminal accessory is too high andthe aging problem of insulation，an on-line monitoring system is designed for medium voltage cable terminal fault，and gives the hardware circuit structure principle of the system and each module design. The lower computer takesMSP430F149 as the core，sets the temperature sensor，the fault current sensor，the high voltage electricity sensor in an integrated detection unit，which is composed of a cable terminal intelligent detection unit. Each cable terminalmonitoring unit of the data using GSM wireless transmission mode to a summary of the LABVIEW platform based onthe development of the wireless terminal of the host computer real-time display and storage. By building the hardware circuit，the temperature of the joint，the fault of the circuit and the remote on-line monitoring of the charged state information are realized，which proves the rationality of the system design.