Objective To evaluate the predictive value of CURB-65 score combined with blood urea nitrogen to albumin ratio (B/A) for intensive care unit (ICU) admission and death in adults with community-acquired pneumonia (CAP). Methods A retrospective analysis was performed on 523 patients with CAP hospitalized in the Second Affiliated Hospital of Kunming Medical University from January 2018 to January 2022. According to whether the patients were admitted to ICU, they were divided into an ICU group (n=36) and a general ward group (n=487). The patients were divided into a death group (n=45) and a non-death group (n=478) according to the death situation during hospitalization. Basic data (age, gender, history of underlying diseases, etc.), hospital stay, antibiotic use days, CURB-65 score, white blood cell count (WBC), neutrophil count (NEUT), procalcitonin (PCT), C-reactive protein (CRP), serum albumin (Alb), blood urea nitrogen (BUN), and BUN to Alb ratio (B/A) of the two groups were compared respectively. Receiver operating characteristic (ROC) curve were plotted to evaluate the predictive value of CURB-65 score, B/A, and their combination for death during ICU admission and hospitalization in patients with CAP. Logistic regression was used to analyze risk factors for in-hospital death in the patients with CAP. Results The number of days in hospital, the number of days of antibiotic use, the number of deaths during hospitalization, the proportion of hypertension, diabetes, CURB-65 score, WBC, NEUT, PCT, CRP, BUN and B/A in the ICU group were significantly higher than those in the general ward group. Age, male, combined hypertension, diabetes, coronary heart disease, ICU admission, CURB-65 score, WBC, NEUT, PCT, CRP, BUN and B/A in the death group were significantly higher than those in the non-death group, and Alb in the ICU group and the death group were significantly lower (all P<0.05). Correlation analysis showed that B/A was positively correlated with PCT, CRP, WBC, NEUT and CURB-65 scores (correlation coefficient r values were 0.486, 0.291, 0.260, 0.310, 0.666, all P<0.001). The area under ROC curve of CURB-65 combined with B/A to predict ICU admission and death of CAP patients was 0.862 (95%CI 0.807 - 0.918, sensitivity 91.7%, specificity 66.4%) and 0.908 (95%CI 0.864 - 0.952, sensitivity 93.3%, specificity 75.7%), respectively. Multivariate logistic regression analysis showed that diabetes, high CURB-65 score, low Alb level and B/A≥4.755 mg/g were independent risk factors for death of CAP patients during hospitalization (P<0.05). Conclusions There is a significant correlation between elevated B/A and ICU demand and mortality in CAP patients. Combined use can improve the predictive value of CURB-65 score for ICU admission and mortality in CAP patients.