Abstract: Objective: To observe the changes in coagulation function during orthotopic liver transplantation,analyze the causes of abnormal coagulation function and explore the use of protamine. Methods: Native thrombelastograph（TEG）and heparinase-modified TEG were measured 60min in pre-anhepatic phase,30min in anhepatic phase,10min in neohepatic phase,respectively.Protamine 25-50mg was given by intravenous injection when R time（R₀）measured by native TEG in neohepatic phase was ＞5min than R time（R₁）measured by heparinase modified TEG.Native TEG and heparinase-modified TEG were measured 10min after injection of protamine.When R₀ in neohepatic phase was ＜5min than R₁,native TEG and heparinase-modified TEG were measured 60min in neohepatic phase and no protamine was given. Results: At 10min in neohepatic phase,R₀ was significantly prolonged than R₁ in 70% of patients.Furthermore,their K value was significantly higher,angle value became lower and MA value decreased.After injection of 25-50mg protamine,the changes in coagulation function became normal. Conclusion: Most orthotopic liver transplantation patients have coagulation abnormalities caused by heparin activity in early neohepatic phase.Intravenous injection of protamine can reverse the effect of heparin and heparin-like substances on coagulation function.