Objective: To measure the level of T-lymphocyte subsets and immunoglobulin in severe traumatic brain injury and to explore the clinical significance. Method: 48 cases with severe traumatic brain injury were measured in T-lymphocyte subsets and immunoglobulin of vein blood before and after the rehabilitation therapy. By comparing with the control group and combining clinical evaluation to analyze the immune functional state in the state of TBI and the prognosis. Result:The cellular and humoral immune were inhibited distinctly. The level of CD3 + ,CD4 + ,CD4 +/CD8 +, IgG and IgA of TBI group were lower than the level of the control group. In prognosis, the early immune state of severe disability+vegetable state group was inhibited more seriously than good recovery + mild disability group. Conclusion: The cellular and humoral immune of severe traumatic brain injury were in inhibited state. The severe inhibition of immune, the worse the prognosis.