Objective:To observe acid-base and biochemical changes in clinical orthotopic liver transplantation with veno-venous bypass.Method,Seven patients receiving orthotopic liver transplantation, veno-venous bypass was undergone in anheptic phase.The acid-base and biochemical parameters were monitored during operation. Result:Compared to preoperation,pH decreased a little in each phase,BE and SBC slightly decreased 60 min following bypass and during skin closure. Compared to before bypass,pH had no changes during bypass and new liver phases. The serum Ca~(2+) level decreased and serum glucose level elevated in each phase,The temperature gradually decreased during operation. The serum K~+ level was transiently elevated from 3.17mmol/L to 3.53 mmol/L early after the heptic revascularizaton. Conclusion:With the application of the veno-venous bypass technique,the hazard of acid-base and biochemical changes can be reduced during orthotopic heptic transplantation.