Objective:To evaluate the dynamic changes in fibrinolytic states after initial resuscitation in severe trauma patients, and to analyze the relationship between the changes and clinical outcomes.Methods:A prospective cohort study was conducted on severe trauma patients admitted to the trauma center in Taicang Hospital, affiliated with Soochow University, from July 2021 to December 2022. Resuscitation treatments, including tranexamic acid (TXA), were administered. Thromboelastography was performed at three intervals: upon admission, 1 hour and 8 hours after initial resuscitation. Fibrinolytic states were categorized into three phenotypes based on clot lysis at 30 minutes: fibrinolysis shutdown (SD), physiologic fibrinolysis (PY), and hyperfibrinolysis (HF). The primary outcomes included all-cause mortality at 24 hours and 28 days. Multivariate logistic regression was used to analyze the association between early fibrinolytic changes and clinical outcomes.Results:A total of 132 patients with severe trauma were included. Upon admission, fibrinolytic phenotypes were distributed as follows: SD in 61 patients (46.2%), PY in 59 patients (44.7%), and HF in 12 patients (9.1%). After resuscitation with TXA and other interventions, SD and PY remained predominant, whereas HF further decreased. Compared with the SD and PY groups, the HF group had significantly higher 24-hour mortality (25.0% vs. 3.3% vs. 3.4%, P<0.05) and 28-day mortality (58.3% vs. 32.8% vs. 11.9%, P<0.05), with massive hemorrhage being the primary cause of death. Among the non-HF groups, 28-day mortality was significantly higher in the SD group than in the PY group (32.8% vs. 11.9%, P<0.05), with traumatic brain injury as the leading cause of death. After the exclusion of 12 HF patients, multivariate logistic regression showed that after adjusting for age, Glasgow Coma Scale score ≤ 8, prothrombin time, and 24-hour crystalloid infusion volume, identified persistent SD was a risk factor for 28-day mortality in severe trauma patients, compared with sustained PY status ( OR=7.009, 95% CI: 1.141-43.079, P=0.036). Conclusions:In patients with severe trauma, SD and PY are the predominant fibrinolysis phenotypes after initial and early resuscitation. Persistent SD following resuscitation is significantly associated with an increased risk of 28-day mortality.