On many occasions, gas phase and liquid phase of original mixture needed to be measured in the processes of petroleum, chemical, natural gas and other industry. A system of gas-liquid separation and metering were studied deeply in this paper. Kingview was taken as the software of the system. It realized dynamic show of the system state and generated various reports. Three of the functional modules were mainly introduced in the software design. The nucleus part of the system was the PID module. Its function was to regulate the aperture of the valve properly. The interface design of supervisory and report management is also described in detail. The testing on the spot has proved that system function and accuracy can meet the needs completely. The system has the characteristics of reasonable structure and stable performance. It provided a better solution to the means of gas-liquid separation.