Background: Helicobacter pylori (H. pylori) can be topically eradicated in stomach lumen on endoscopic examination. The procedures of intraluminal therapy for H. pylori infection (ILTHPI) include the control of intragastric pH, mucolytic irrigation of the gastric mucosal surface, and a single-dose medicament containing antimicrobial agents. Aims: To detect gastric juice pH and evaluate its impact on the success rate of ILTHPI. Methods: We enrolled 324 patients with upper abdominal discomfort for endoscopic examinations. Among them, 13C-urea breath test was positive in 218 patients, where 100 underwent ILTHPI, and negative in 106. All patients had their gastric juice pH detected and set into three ranges, including normal acidity (pH < 4.0), low-level hypoacidity (pH 4.0–5.5), and high-level hypoacidity (pH ≥ 6.0). The impact of gastric juice pH on the success rate of ILTHPI was evaluated. Results: Distribution of pH level showed no significant difference between two groups of H. pylori-infected patients (p = 0.942). The eradication rate of ILTHPI is significantly lower in patients with gastric juice pH below 4 (p < 0.001). Conclusions: Detection of gastric juice pH in ILTHPI is extremely important. Rapid control of stomach pH at or above 4 for patients prior to ILTHPI is strongly recommended. (NCT03124420).