Achalasia is a rare esophageal motility disorder, characterized by incomplete lower esophageal sphincter relaxation, increased Lower esophageal sphincter (LES) tone, and aperistalsis of the esophagus. Typical clinical symptoms are dysphagia,regurgitation and chest pain. Traditional treatments include endoscopic balloon dilatation or botulinum toxin injection, laparoscopic Heller myotomy with or without a partial fundoplication. Peroral endoscopic myotomy (POEM) has been developed as a further endoscopic effective and minimal invasive treatment. The aim of this study is to investigate the efficacy and safety of POEM in our department, and to assess short-term and long-term efficacy of POEM by using Stooler score, Echardt score, esophageal barium and manometry.