Gas wells in the SM gas field generally produce water, resulting in liquid accumulation in the wellbore and the need for liquid drainage. Currently, studies on liquid accumulation prediction are rather difficult to be applied in actual production and have poor generalization. The critical liquid-carrying flow rate of the wellbore in the SM gas field was obtained through numerical simulation and extended to 57 gas wells, with relatively high prediction accuracy. Three high-precision multiphase flow transient wellbore models were established based on MATLAB software for simulation analysis. The simulation results indicate that the critical liquid-carrying flow rate of gas wells in the SM gas field is approximately 3.07 m/s. When the gas well flow rate is greater than the critical liquid-carrying flow rate, various flow parameters in the wellbore quickly reach a steady state, and the liquid holdup is below 2.5%, suggesting no liquid accumulation at this time. When the gas well flow rate is less than the critical liquid-carrying flow rate, the liquid holdup in the wellbore is high, and the pressure loss in the high liquid holdup pipe section is considerable. Based on this critical liquid-carrying flow rate, the critical liquid-carrying flow rate diagrams for 1.38 in(1 in = 2.54 cm) and 1.61 in tubing are plotted. When this diagram is applied to the field, the prediction accuracy reaches 89.5% and can be used to guide the on-site liquid drainage work.