Traumatic brain injury(TBI)triggers the acti-vation of the endogenous coagulation mechanism,and a large amount of thrombin is released to curb uncontrollable bleeding through thrombin receptors,also known as protease-activated receptors(PARs).However,thrombin is one of the most critical factors in secondary brain injury.Thus,the PARs may be effective targets against hemor-rhagic brain injury.Since the PAR1 antagonist has an increased bleeding risk in clinical practice,PAR4 blockade has been suggested as a more promising treatment.Here,we explored the expression pattern of PAR4 in the brain of mice after TBI,and explored the effect and possible mechanism of BMS-986120(BMS),a novel selective and reversible PAR4 antagonist on secondary brain injury.Treatment with BMS protected against TBI in mice.mRNA-seq analysis,Western blot,and qRT-PCR verifica-tion in vitro showed that BMS significantly inhibited thrombin-induced inflammation in astrocytes,and sug-gested that the Tab2/ERK/NF-κB signaling pathway plays a key role in this process.Our findings provide reliable evidence that blocking PAR4 is a safe and effective intervention for TBI,and suggest that BMS has a potential clinical application in the management of TBI.