Abstract: Liquid column is formed in the wellbore due to the long-time liquid loading, while the gas flow rate is not so high that the liquid could be carried over the wellbore. As a result, two-phase flow gas lifting area exists in the wellbore, and the liquid flow rate is zero in the well head. The phenomenon is called liquid flow rate being zero, and it is a special flow-pattern of water production gas wells. It matches to point of gas lift. In this paper, the criteria for the classification of flow patterns, the mathematical model for calculating the pressure drop and liquid holdup rate are presented. Also a self-designed visual experiment bench is established to simulate the phenomenon. Advanced testing methods are adopted in the experiment to acquire the photographs of the flow patterns and the data of pressure drop, wellhead pressure, gas injectioin volume, and liquid holdup rate. Through theoretical calculations and experimental data comparison, the theoretical model is proved to be correct. Finally, examples are given to simulate gas flow with zero liquid flow and non-slip gas-liquid two-phase flow of actural gas wells. The research results are useful to drainage design of gas wells with severe liquid loading.