Sleeve gastrectomy (SG) is currently the most frequently performed bariatric procedure, yet it faces limitations such as inadequate weight loss or regain, gastroesophageal reflux disease (GERD), and intrathoracic sleeve migration (ITSM), necessitating refinement. To address these shortcomings, this study proposes the novel concept of functional sleeve gastrectomy (FSG). FSG aims to systematically optimize surgical techniques to resolve these issues, achieving maximal organ function preservation, optimal weight loss outcomes, and minimal complications. The core innovations of FSG include: routine exploration of the left diaphragmatic crus; plication and narrowing of the costodiaphragmatic angle; preservation of approximately 2 cm of gastric fundal tissue proximal to the angle of His; construction of a gastric body restriction ring; initiating gastric transection 3~4 cm proximal to the pylorus; seromuscular imbrication suturing of the staple line; and omentum repositioning and fixation. Preliminary application in 12 patients demonstrates: the procedure is safe and feasible (with no severe complications); at 12 months postoperatively, mean total weight loss (%TWL) reached (34.8±7.9)% and mean excess weight loss (%EWL) was (77.2±18.9)%. Notably, none of the patients reported typical GERD symptoms. FSG may represent a novel direction for optimizing SG, However, further research evidence is still needed to prove the safety and effectiveness of FSG, so as to provide a reference basis for the promotion of this surgical method.