Abstract: Objective To investigate the diagnostic value of serum procalcitonin (PCT) and interleukin-1β (IL-1β) in severe traumatic brain injury patients with hospital acquired pneumonia (HAP). Methods From March 2015 to March 2018, 138 patients with severe traumatic brain injury admitted to the Third People's Hospital of Hainan province were selected. They were divided into HAP group (n=57) and non-HAP group (n=81) according to whether they had hospital acquired pneumonia or not. The changes of serum PCT and IL-1β levels in two groups at day 1, day 3, day 7 after admission were compared. The predictive value of serum PCT and IL-1β levels in each time point for HAP was analyzed using ROC curve. Results Serum PCT and IL-1β levels in the HAP group were significantly higher than those in the non-HAP group at day 3 and day 7 (all P< 0.05). In HAP group, serum levels of PCT and IL-1β significantly increased over time (all P< 0.05). The ROC curve showed that the AUC (95% CI) of HAP patients with severe brain injury diagnosed by combination of PCT and IL-1β at day 3 was 0.908 (0.847-0.969), which was significantly higher than that of PCT 0.824 (0.765 - 0.884) or IL-1β 0.817 (0.756 - 0.872), and its sensitivity and specificity were 91.2% and 86%, respectively. Conclusion Combination of PCT and IL-1β at day 3 is helpful to improve the diagnostic value of hospital acquired pneumonia in patients with severe traumatic brain injury.