【Abstract】 Objective To investigate the preventative effect of large intravenous infusion in early period for postERCP pancreatitis (PEP) with choledocholithiasis.Methods 80 patients underwent ERCP for choledocholithiasis between January 2014 and November 2014 were randomly divided into the preventive group and the contrasted group. Each group had 40 patients. Patients in the preventative group and the contrasted group started to transfuse intravenous infusion one hour before ERCP. The preventive group infused ringer's solution 40ml/h. The contrasted group infused ringer's solution 25ml/h. After operation, all the patients were given treatments of acid suppression, preventative anti infection and hemostasia. All the patients in these 2 groups were measured their level of serum amylase 3 hours before ERCP, and were measured them again 3 hours, 12 hours and 24 hours after ERCP. We also recorded their abdominal symptoms and signs. Results The volume of infusion of the preventative group in 24 hours（32155±482）ml was higher than that in the contrasted group (22208±524) ml(ｐ﹤005). The volume of serum amylase in the preventative group 3 hours, 12 hours and 24 hours after ERCP was (515±413),(588±468)and(520±455)U/L respectively. These facts were significantly lower than those in the contrasted group(ｐ﹤005). The facts in the contrasted group were (762±614),(1526±1624)and(1249±1166)U/L. The occurrence of hyperamylasemia and pancreatitis in the preventative group (75%、25%) was significantly lower than that in the contrasted group (425%、150%)(ｐ﹤005).Conclusion The early large intravenous infusion may effectively prevent the occurrence of hyperamylasemia and PEP.