Background: Sepsis-associated encephalopathy (SAE) is a common encephalopathy in ICU. We are to definite whether SAE present an high prevalence rate and early risk factors for death in ICU 48 hours, while to cognize its important of early prevention/ control.Methods: We retrospectively enrolled patients with acute critically ill from ICU (January, 2015 to January, 2017). All patients were selected from onset to ICU ā¤3 hours. The prevalence and some early risk factors of death in SAE was estimated by using a continuous head and thorax /abdominal cavity CT scans. Results: 748 critically ill adults were analyzed. The prevalence of sepsis within initial 48 hours was 40.4% (302/748). The median time from infection to sepsis was 9 hours ( range, 1-48 ). The SAE (93.4%, 282/302) was diagnosed in sepsis patients, and most of them (96.8%) presented multiple organ dysfunction syndromes (MODS). While the fatality of SAE was in 32.0% at initial 48 hours and 69.1% at initial 14 days. Cox regression analysis, unused antibiotic within initial 3 hours (OR, 0.39; 95% CI, 0.22-0.89), severe inflammatory storm (OR, 0.70; 95% CI, 0.58- 0.94), lower GCS (OR, 2.7; 95% CI, 1.5-3.6), and MODS (OR, 0.37; 95% CI, 0.26-0.96) were early risk factors for death in SAE. Early risk factors for predicting SAE were related to severe inflammatory storm (OR, 3.10; 95% CI, 2.28-4.33), MODS (OR, 3.57; 95% CI, 2.73- 4.67), and unused antibiotics within initial 3 hours (OR, 0.25; 95% CI, 0.11-0.56).Conclusions: SAE in ICU is an high prevalent acute brain dysfunction and most with MODS. The early bad prognosis in SAE was related to the failure of early prevention and control.