Abstract: Faulty shut-off operation of gas-liquid valve had occurred time after time in Zhongxian-Wuhan Gas Transmission Pipeline after its commissioning.Analysis results display that one of the mam causes of the faulty shut-off operation in the gas-liquid valve is the misselection of equipment.which results in low reliability of power supply system, and the other is the defects existed in equipment itself.Technical modification measures on improving power supply system, strengthen insulating protection and perfecting control software are proposed.