Objective:To investigate the correlation between soluble growth stimulating gene protein 2 (sST2) and the severity of traumatic brain injury (TBI) and its value in the diagnosis of traumatic brain injury.Methods:The clinical data of 110 patients with traumatic brain injury who were treated in The First Affiliated Hospital of University of Science and Technology of China (Anhui Province Hospital) from July 2022 to December 2022 were retrospectively analyzed. These 110 patients were included in the observation group. An additional 62 patients without traumatic brain injury who concurrently received treatment in the same hospital were included in the control group. In the observation group, patients were divided into a severe group [Glasgow Coma Scale (GCS) score 3-8 points), a moderate group (GCS score 9-12 points), and a mild group (GCS score 13-15 points) according to the GCS score. Serum sST2 levels were measured using enzyme-linked immunosorbent assay (ELISA) within 24 hours after injury in each group. Serum sST2 levels were compared between the observation group and the control group. Serum sST2 levels were compared among patients with severe, moderate, and mild TBI in the observation group to analyze the correlation between serum sST2 levels and the GCS score. The efficacy of serum sST2 levels in the diagnosis of TBI was evaluated using the receiver operating characteristic curve (ROC curve).Results:Serum sST2 levels in the observation group were 96.25 (48.05, 200.00) μg/L, which were significantly higher than 25.45 (19.78, 40.46) μg/L in the control group ( Z = -8.19, P < 0.05). Serum sST2 levels in pastients with severe TBI were slightly, but not significantly, higher than those in patients with moderate TBI ( P > 0.05), and serum sST2 levels in patients with severe and moderate TBI were significantly higher than those in patients with mild TBI ( Z = -5.20, Z = -4.40, both P < 0.05). There was a significant difference in sST2 levels among patients with mild, moderate and severe TBI ( H = 36.88, P < 0.05). In the observation group, serum sST2 levels within 24 hours after surgery were significantly negatively correlated with GCS score within 24 hours after admission ( rs = -0.561, 95% CI: -0.680~-0.413, P < 0.001). As serum sST2 levels increased, GCS scores showed a decreasing trend. Serum sST2 levels can be used as a prognostic indicator for TBI. Serum sST2 levels within 24 hours after injury can serve as a risk factor for TBI ( β = 0.042, OR = 1.043, 95% CI: 1.026-1.061, P < 0.001). The serum sST2 levels within 24 hours after injury have good diagnostic efficacy for TBI (area under the curve = 87.5%, 95% CI: 0.825-0.926, P < 0.001). Conclusion:The measurement of serum sST2 levels has a high value in the evaluation of the severity of TBI and prognosis, which is crucial for developing personalized treatment strategies for TBI.