The detection of special anti-mycobacterial antibodies in cerebrospinal fluid (CSF) were evaluated. Among all the common coated antigens, it was found that PPD was the most potential one. Seven detecting methods were compared. It is shown that the classic ELISA technique is worth recommending. The results of the experiments, revealed that absorbance method was better than titration method, IgG antibody was more sensitive than IgM antibody and the sensitivity rate of IgM was not related with the course of the disease. The factors which influenced the levels of IgG antibody to mycobacterial antigens include focal signs and abnormal CT findings. False positive results were found in detecting anti-mycobacterial antibodies in a few cases. Immunodiagnosis was an useful method in diagnosing tuberculous meningitis and this study has provided ample theoretical basis for popularizing this technique.