The normal cerebrospinal fluid is colorless and transparent, but in pathological cases, the blood-brain barrier can be disrupted to change the composition of the cerebrospinal fluid. 1, bloody cerebrospinal fluid is mostly seen in cerebral hemorrhage and subarachnoid hemorrhage, and needs to be differentiated from injury hemorrhage, which is mostly caused by unsuccessful puncture or local vascular rupture during the puncture process. 2, the lumbar puncture process is smooth without obvious damage to the three tube test, the cerebrospinal fluid color does not become lighter phenomenon, consider cerebral hemorrhage or subarachnoid hemorrhage, both diseases can be life-threatening diseases need to go to the hospital for active treatment.