The clinical data of 4 pediatric patients with collagenous gastritis (CG) diagnosed at the Department of Pediatrics of Peking University Third Hospital between January 2021 and October 2025 were retrospectively analyzed. The median age at onset was 10.8 years. All patients presented with iron-deficiency anemia, and two also experienced abdominal pain. Gastroscopy in all cases revealed a nodular gastric mucosal appearance. Histopathological examination confirmed subepithelial collagen band thickness greater than 10 μm in all patients, with varied patterns of inflammatory infiltrate, including two cases with eosinophil-predominant inflammation and one with lymphocytic gastritis. Two patients were found to have collagenous duodenitis, while none showed collagenous colitis. Serological testing identified one patient with low-titer positive antinuclear antibodies and another with elevated gastrin-17 levels. Treatment consisted of iron supplementation in all cases, combined with gastric mucosal protectants in three patients and glucocorticoid therapy in one patient. Follow-up of three patients showed clinical improvement with resolution of anemia, and two also demonstrated histological improvement with reduced gastric inflammation and collagen deposition. Pediatric CG is characterized primarily by iron-deficiency anemia and nodular gastric mucosal changes, accompanied by duodenal involvement in some patients. These findings underline the importance of a comprehensive evaluation of the entire gastrointestinal tract. Diagnosis relies on distinct endoscopic and pathological features, while attention should also be paid to potential biomarkers. A combined treatment approach, including iron supplementation, mucosal protection, and glucocorticoids when necessary, may lead to clinical and histological remission.