Background: Hypoxemia is a major complication in obese patients undergoing gastrointestinal endoscopy under intravenous anesthesia or sedation due to altered airway anatomy. We design this randomized controlled trial (RCT) to compare efficacy and safety of the Wei nasal jet tube (WNJT) and nasal prongs for supplement oxygen during gastroscopy with intravenous propofol anesthesia in obese patients. Methods: The study will be a single-center, prospective RCT. A total of 308 obese patients will be recruited and randomly assigned to receive either the WNJT (group A) or nasal prongs (group B). During gastroscopy with intravenous propofol anesthesia, 5 L/min of oxygen will be delivered through the jet port of the WNJT in the group A and via the nasal prongs in the group B. The primary outcome is the incidence of hypoxemia and severe hypoxemia. The secondary outcomes are adverse events during the gastroscopy, postoperative complications, and satisfaction of the anesthetist, physician, and patient. Discussion: This RCT aims to clarify whether the WNJT can result in reduced incidences of hypoxemia and complications and provide improved satisfaction to the anesthetist, physician, and patient. Thus, it can be determined if the WNJT is a useful tool for supplement oxygen in obese patients undergoing gastroscopy with intravenous propofol anesthesia. The results will provide the evidence for anesthesiologists to make a decision regarding the choice of supplementary oxygen methods in this condition.