IntroductionAbnormal coagulation function aggravates the prognosis of patients with traumatic brain injury (TBI). It was reported that the antifibrinolytic drug tranexamic acid (TXA) could reduce intracranial haemorrhage and mortality in non-operative patients with TBI. However, there is a lack of evaluation of TXA in patients with TBI undergoing craniotomy.Methods and analysisThis is a single-centre randomised controlled, double-blind, parallel study aiming to investigate the effectiveness and safety of TXA in patients with TBI during the perioperative period. Blood loss and transfusion, neurological function, adverse events, mortality and serum immune-inflammatory cytokines will be collected and analysed.Ethics and disseminationEthical approval has been granted by the Medical Ethics Committee of Beijing Tian Tan Hospital, Capital Medical University (reference number KY 2020-136-03). The results of this study will be disseminated through presentations at scientific conferences and publication in peer-reviewed journals.Trial registration numberChiCTR2100041911.