Intrathoracic gastric duplication has rarely been reported. A 5-year-old child with gastric duplication located in the left thorax was diagnosed and treated successfully using laparoscopy combined with gastroscopy. Preoperative computed tomography, upper gastrointestinal contrast study, ultrasound, and other imaging methods were insufficient for accurate diagnosis in this case. Laparoscopy combined with gastroscopy is more suitable for the diagnosis and treatment of gastric duplication.