Objective To investigate the efficacy and safety of gastric peroral endoscopic myotomy (G-POEM) in the treatment of postsurgical gastroparesis. Methods A retrospective analysis was performed on data of 47 patients with gastroparesis after subtotal gastrectomy, who underwent G-POEM in the Zhongda Hospital Southeast University form August 2016 to June 2018. G-POEM procedure, complications related to G-POEM, and improvement of symptoms and gastric emptying function were observed. Results All patients underwent G-POEM successfully. No serious G-POEM-related complications were observed．During a follow-up period of 9.8±5.8 months (range 3-18 months), the score of gastroparesis cardinal symptoms index (GCSI) was 1.6±0.5, 1.2±0.4, 1.1±0.6, 1.4±0.3 and 1.7±0.3 respectively at the 1st, 3rd, 6th, 12th, and 18th months after G-POEM, and all scores were lower than that before G-POEM (3.8±1.1, all P<0.01). The results showed the symptoms of gastroparesis were improved significantly. Gastric emptying imaging showed the hemi-emptying time was 23.8±8.8 min, 21.2±9.5 min, 20.9±8.3 min and 26.4±7.8 min at the 1st, 6th, 12th and 18th months after G-POEM, respectively. All of the time were significantly shorter than that before G-POEM (67.8±12.5 min, all P<0.01). Three-dimensional ultrasonography results of gastric antrum volume showed that the hemi-emptying time was 26.4 (21.8, 40.3) min, 22.6 (13.9, 32.7) min, 24.3 (18.2, 36.5) min and 26.8 (16.4, 38.5) min at the 1st, 6th, 12th and 18th months after G-POEM, respectively, which were all significantly shorter than that before G-POEM [72.5 (48.3, 108.6) min, all P<0.01]. Conclusion G-POEM has a satisfactory long-term efficacy on the treatment of gastroparesis after subtotal gastrectomy, with a good safety.