Abstract: The influence law of tubing depth on the liquid drainage effect of horizontal gas wells was explored. The influence of different structural tubing depths on the wellbore drainage effect of horizontal oil tubes was revealed through experiments. Based on the principle of geometric structure similarity, a large-scale visualizable experimental device with adjustable horizontal section angles and variable tubing depths was designed and built. The flow laws of gas wells in the start-up, stable production and end-of-production stages under different tubing depths (the distance from point A to the target point accounts for 4% to 96% of the horizontal section length) and different gas flow rates (gas flow rate of 20 to 100 m³/h) in both upward and downward inclined structures were simulated. The flow patterns were observed, and the dynamic laws of lift pressure drop and liquid holdup were tested.For downward inclined horizontal wells, the greater the tubing depth, the greater the bottom hole pressure required for well opening and start-up, and the more difficult it is to start the gas well after liquid accumulation. The total pressure drop of the wellbore with tubing placed at the toe end is 26.92% lower than that with tubing placed at the heel end, which is beneficial to improving the recovery rate of the gas well during the self-flowing liquid production stage. For upward inclined horizontal wells, the opposite is true compared to downward inclined horizontal wells. The total pressure drop of the wellbore with tubing placed at the toe end is 15.92% higher than that with tubing placed at the heel end, and the stable production time is shorter, which is not conducive to increasing production.For downward inclined horizontal wells, it is recommended to place the tubing near the toe end; for upward inclined horizontal wells, it is recommended to place the tubing near the heel end.