Objective To evaluate the value of the initial blood lactic acid monitoring in the elderly patients with multiple traumas. Methods A total of 78 elderly patients with multiple traumas admitted in our ICU from November 2012 to July 2013 were enrolled in this study and retrospectively analyzed. Immediately after hospitalization, their arterial blood samples were immediately collected for blood gas analysis. According to the arterial lactic acid level, these patients were divided into 3 groups: arterial lactic acid level ＜2mmol/L group, 2 to 4mmol/L group and ＞4mmol/L group. Based on the basic information and clinical data, their acute physiology and chronic health evaluation (APACHE) Ⅱ score within 24h, ICU stay duration, incidence of infection, number of failed organs, fluid intake within 24h and hospital mortality were compared among the different groups. Finally, all the patients were also divided into survival group and death group according to their prognosis. The risk factors influencing the prognosis were analyzed by univariate and multivariate logistic regression analysis. Results There was no significant difference in demographic and medical data in the above 3 groups after admission. Their APACHEⅡ score, fluid intake within 24h, number of failed organs, ICU stay duration, and hospital mortality were significantly different in the 3 groups (P＜0.05). There was no significant difference in the initial systolic blood pressure and incidence of infection (P＞0.05). Multivariate regression analysis showed that the number of failed organs and initial lactate level were independent risk prognostic factors in the elderly patients with multiple trauma. Conclusion The initial blood lactic acid is an important monitoring index in clinical treatment for the elderly patients with trauma, and is also of great importance to evaluate prognosis.