Objective To exlpore the relationship between serum levels of cholinesterase and severity and prognosis of sepsis. Methods 50 patients defined as sepsis were assigned into 2 groups according to the APACHE-II score within 24 hours of admission. The patients whose APACHE-II score ≤ 20 were assigned into Group A. The patients whose APACHE-II score 〉20 were assigned into Group B. The contents of serum cholinesterase in group A and group B were determined within 24 h of hospital to analyze its relationship with APACHE-II score. Results The serum cholinesterase level was negatively correlated with APACHEII score（r =-0.444, P =0.05）. The serum cholinesterase level in group B was significantly lower than that in group A（P〈0.05）, and the serum cholinesterase level in death group was significantly lower than that in survival group（P〈0.05）. Conclusion The determination of serum cholinesterase is valuable for early assessment of the severity and prognosis of sepsis.