Objective: To investigate the application of 24-hour esophageal pH monitoring in children with suspected gastroesophageal reflux disease (GERD). Methods: From March 2017 to June 2018, 119 children with suspected gastroesophageal reflux (GER) who were suspected of having gastroesophageal reflux (GER) were enrolled in the outpatient clinic of Chengdu Women and Children’s Center Hospital for 24 h esophageal pH. monitor. According to their main clinical manifestations, they were divided into three groups: group A was typical reflux symptoms; group B was atypical reflux symptoms; group C was extra-gastrointestinal symptoms, including 60 cases in group A, 29 cases in group B, and 30 cases in group C. The total pH value of the three groups of pathological GER patients <4 time of percentage, standing pH value <4 time percentage, lying pH value <4 time percentage, pH <4 reflux number, the times of acid reflux >5 min were compared. The number of times, the longest reflux duration, the Boix-Ochoa score, the acid reflux index and other indicators. Results: A total of 60 patients in group A, 40 (66.67%) were pathological GER; 29 patients in group B, of which 20 (68.97%) were pathological GER; 30 patients in group C, 20 (66.67%) of which were pathological GER. There was no significant difference in the positive rate of pathological GER between the three groups (P>0.05). The total pH value of the three groups of patients with pathological GER was <4 time of percentage, the standing pH value was <4 time percentage, and the lying position pH value <4 time percentage, pH <4 reflux number, the times of acid reflux >5 min, longest reflux duration, Boix-Ochoa score, acid reflux index were not statistically significant (P>0.05). Conclusion: 24 h esophageal pH monitoring plays an irreplaceable role in the diagnosis and efficacy evaluation of GERD. It is recommended for GERD, non-erosive reflux disease (NERD) for atypical reflux symptoms or extra-gastrointestinal symptoms, or children with poor anti-reflux medications.