Abstract: Liquid loading in gas well will bring serious damage on gas field and the gas well self. In order to cope with this problem, accurate diagnosis the situation and the time of bottom hole liquid loading becomes the crucial step. Critical rate is one of the methods be common used. Based on the Turner model, this paper take the bottom of wellhole as control condition, study the influence of reservoir pressure, wellheard pressure, the size of tubing, water -gas ratio on critical rate, analyze their respective sensitivity, and point out the suggestion on preventing liquid loading. Considering the production performance of SeBei gas field, comparative analyze five kinds critical rate calculation model used often now. Then selected kinetic energy factor model, the minimum kinetic energy factor is 10.