Objective To investigate the effects of probiotics combined with early enteral nutrition on levels of endothelin-1 (ET-1), C-reactive protein (CRP), and inflammatory factors, and on the prognosis of patients with severe traumatic brain injury (TBI). Methods We enrolled 76 adults with severe TBI. The patients were divided randomly into two equal groups administered enteral nutrition with and without probiotics, respectively. Demographic and clinical data including age, sex, Glasgow Coma Scale score, Sequential Organ Failure Score, Acute Physiology, Chronic Health Score, hospitalization, mortality, and infections were recorded. Results Serum levels of inflammatory factors gradually decreased with increasing treatment time in both groups. However, ET-1 at 15 days, and interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α, and CRP at 7 and 15 days decreased significantly more in the combined treatment group. Hospitalization duration and pulmonary infection rates were also significantly reduced in the combined compared with the enteral nutrition alone group. GCS scores at 15 days were significantly lower in the combined compared with the enteral nutrition group. Conclusion Probiotics combined with early enteral nutrition could reduce serum levels of ET-1, CRP, and IL-6, IL-10, and TNF-α, and could thus improve the recovery of patients with severe TBI.