Objective To investigate the risk factors for portal vein thrombosis (PVT)under anticoagulation therapy after surgery in patients with portal hypertension.Methods We made a retrospective analysis of clinical data of 96 portal hypertension patients for surgical treatment at our hospital.All the patients with postoperative PVT or without were divided into two groups.Risk factors that may predict PVT were analyzed.Results PVT developed in 41 (40.08%)of 96 patients after surgery.Risk factors such as sex,age,Child-Pugh classification,type of operation,portal pressure and the pressure difference before and after surgery,preoperative prothrombin time, preoperative platelet count,spleen index,and portal vein diameter were not predictors of PVT.However,splenic vein diameter was an independent risk factor for PVT (P = 0.036);postoperative PVT tended to develop when the splenic vein diameter was larger than 1 1 mm.Conclusion Preoperative color Doppler testing of splenic vein diameter can predict PVT after surgery in patients with portal hypertension.