Abstract: Objective To access the causes of hypouricemia and its relationship with prognosis in patients with traumatic brain injury (TBI). Methods A total of 104 TBI patients who were admitted in the Affiliated Hospital of Xuzhou Medical University from June 2018 to December 2019 were enrolled. According to their uric acid levels, they were divided into two groups (n=52): a hypouricemia group and a control group.According to their prognosis, they were divided into two groups: a good prognosis group (n=48) and a poor prognosis group (n=56). Their imaging and laboratory data were collected, and their Glasgow coma score and Glasgow prognostic score were recorded as the criteria for evaluating the severity and prognosis of the disease. Results The hypouricemia group presented remarkable increases in female percentage and GCS score as well as decreases in the percentage of subarachnoid hemorrhage (SAH),compared with the non-hypouricemia group (P<0.05). The good prognosis group showed remarkable increases in the incidence of hypouricemia, GCS score and albumin level, as well as decreases in age, compared with the poor prognosis group (P<0.05). The areas under the ROC curve to predict poor prognosis was 0.690 for age, 0.674 for hypouricemia, 0.690 for GCS score at admission, 0.615 for albumin and 0.815 for the combination of the above four factors (P<0.05). Conclusions Sex, SAH and GCS score are the independent influencing factors of hypouricemia in patients with TBI. Hypouricemia is a protective factor for the prognosis of TBI and can be used to predict the prognosis of TBI patients.