The Sulige gas field is one of the typical tight sandstone gas reservoirs in China, the reservoir features high water saturation in the effective reservoir and mixed distribution of gas and water layers. During the middle and late stages of development, the effective development of natural gas is usually hindered by fluid accumulation in the wellbore, and fluid drainage is often required to maintain sustain production. In this paper, a gas lift wellbore drainage model is developed based on the oil casing's mass, momentum, and energy equations, and it is solved using Eulerian difference method. Based on the established gas wellbore drainage model, the degree of influence of different parameters, e.g., gas injection volume and wellhead oil pressure on the drainage efficiency of gas wells has been studied, and variables such as fluid production, gas production and drainage time during gas lift drainage of S wells are analyzed, which provide guidance for improving drainage efficiency of water-producing gas wells in tight sandstone and optimizing gas lift drainage production.