Abstract: Objective To discuss the evaluation value of blood lactic acid level and its clear-ance rate in the prognosis of patients with infectious shock.Methods The clinical data of 88 pa-tients with infectious shock in our hospital from May 2011 to October 2013 were retrospectively ana-lyzed and divided into survival group (48 cases)and death group (40 cases)according to whether the patients were alive or dead after 28 d of hospitalization.The blood lactic acid level,clearance rate of lactic acid as well as Acute Physical and Chronic Health Evaluation Ⅱ (APACHEⅡ)at 6 and 24 h after hospitalization,the survival rate of patients with different clearance rates of lactic acid after 6 h,and the relationship between blood lactic acid level and its clearance rate with the progno-sis were observed.Results There was no significant differences between two groups in the initial level of lactic acid (P >0.05).Survival group was apparently lower in blood lactic acid levels at 6 and 24 h (P <0.01)and obviously higher in their clearance rates than death group (P <0.01). The survival rates of patients with clearance rate ≥10% in 6 h was 91.49%,evidently higher than that of in patients (12.20%)with 6 h clearance rate <10% (P <0.01).Multiple linear regression analysis showed that the clearance rate of lactic acid at 6 and 24 h were the independent influencing factors of patients’death (P <0.01).Conclusion Dynamic detection of blood lactic acid has criti-cal significance in patients with infectious shock,and the clearance rates of lactic acid at 6 and 24 h can be regarded as the main indexes in evaluating patients′prognosis.