Surgical operation in treating obesity and type 2 diabetes is popularizing rapidly in China. Correct prevention and recognition of perioperation-related operative complications is the premise of ensuring surgical safety. Familiar complications of the operation include deep venous thrombosis, pulmonary artery embolism, anastomotic bleeding, anastomotic fistula and marginal ulcer. The prevention of deep venous thrombosis is better than treatment. The concrete measures contain physical prophylaxis (graduated compression stocking and intermittent pneumatic compression leg sleeves) and drug prophylaxis (unfractionated heparin and low molecular heparin), and the treatment is mainly thrombolysis or operative thrombectomy. The treatment of pulmonary artery embolism includes remittance of pulmonary arterial hypertension, anticoagulation, thrombolysis, operative thrombectomy, interventional therapy and extracorporeal membrane oxygenation (ECMO). Hemorrhage is a rarely occurred but relatively serious complication after bariatric surgery. The primary cause of anastomotic bleeding after laparoscopic gastric bypass is incomplete hemostasis or weak laparoscopic repair. The common bleeding site in laparoscopic sleeve gastrectomy is gastric stump and close to partes pylorica, and the bleeding may be induced by malformation and weak repair technique. Patients with hemodynamic instability caused by active bleeding or excessive bleeding should timely received surgical treatment. Anastomotic fistula in gastric bypass can be divided into gastrointestinal anastomotic fistula and jejunum-jejunum anastomotic fistula. The treatment of postoperative anastomotic fistula should vary with each individual, and conservative treatment or operative treatment should be adopted. Anastomotic stenosis is mainly related to the operative techniques. Stenosis after sleeve gastrectomy often occurs in gastric angle, and the treatment methods include balloon dilatation and stent implantation, and surgical treatment should be performed when necessary. Marginal ulcer after gastric bypass is a kind of peptic ulcer occurring close to small intestine mucosa in the junction point of stomach and jejunum. Ulcer will also occur in the vestige stomach after laparoscopic sleeve gastrectomy, and the occurrence site locates mostly in the gastric antrum incisal margin. Preoperative anti-HP (helicobacter pylorus) therapy and postoperative continuous administration of proton pump inhibitor (PPI) for six months is the main means to prevent and treat marginal ulcer. For patients on whom conservative treatment is invalid, endoscopic repair or surgical repair should be considered. Different surgical procedures will generate different related operative complications. Fully understanding and effectively dealing with the complications of various surgical procedures through multidisciplinary cooperation is a guarantee for successful operation.