Objective To study the role of transcranial Doppler (TCD) in early diagnosis of posttraumatic vasospasm in traumatic brain injury patients and in treatment effect monitoring of hyperxia liquid for this condition. Methods Seventy-four patients with posttraumatic vasospasm were divided into two groups. The control group (n=42) received the general treatment, while the treatment group (n=32) received the treatment of hyperxia liquid in addition to the general treatment. Their cerebral blood flow velocities of bilateral MCA and extra-cranial portion of ICA were monitored regularly by TCD, starting from the first day after head injury until 14th day. The changes of physiological and neurofunctional parameters in both groups were compared, including cerebral vasospasm(CVS),arterial blood oxygen pressure (PaO 2),arterial blood oxygen saturation (SaO 2), the Glasgow coma scale (GCS)and the ultimate effects of treatment as indicated by Glasgow outcome scale(GOS). Results Cerebral vasospasm occurred in 1 to 3 days and peaked to the 3 to 7 days after injury, then markedly relieved at 14 days after injury. After infusion of hyperxia liquid, the PaO 2 and SaO 2 in the treatment group were significantly higher than those of the control group. The degree of vasospasm was significantly higher in the control group than that in the treatment group. GCS and GOS of the treatment group were significantly higher than those of the control group. Poor outcome was common in patients with severe cerebral vasospasm. Conclusion Early posttraumatic vasospasm can be detected by TCD. High-oxygen liquid is effective for treating posttraumatic vasospasm.