On the basis of discussing the control process of N2 steel making LT coal gas cooled high pressure feed-water system of Bao Steel,the experimental research on the dynamic circulating control characteristic of open to air check valves system is carried out.According to the enterprise reforming practice of several saving energy techniques and the on the-spot long-term running experiences,the valve system integrates the four functions of flux apperceiving,checking,bypass controlling and multi-grade ruming,which can economically and effectively protect water pump and keep its normal running.Its easy operation and multifunction help feed -water circulating control to reach advanced level.