One anastomotic gastric bypass (OAGB) has become an increasingly adopted bariatric and metabolic surgery in recent years. The International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) and the American Society for Metabolic and Bariatric Surgery (ASMBS) now recognize OAGB as a standard bariatric procedure. Similar to Roux-en-Y gastric bypass (RYGB), OAGB aims to reduce weight, control blood glucose levels, and treat insulin resistance trough decreasing the gastrointestinal tract’s uptake and absorption of nutrients. OAGB features a less complex surgical technique and reduced perioperative risks. However, OAGB is associated with difficult-to-manage bile reflux and higher nutritional deficiency risks than RYGB. The key surgical steps of this procedure include: ①Construction of an 18–20cm gastric pouch along the lesser curvature below the incisura angularis, isolating the gastric fundus; ②Measurement of total small bowel length with 30% bypassed as biliopancreatic limb, maintaining ≥400cm common channel; ③Creation of a Billroth Ⅱ gastrojejunal anastomosis with stoma diameter <3.0cm; ④Placement of the anastomosis at the gastric antrum to minimize torsion risk.