Lumbar puncture, a lumbar puncture to extract cerebrospinal fluid for pathogenetic examination, is mainly used for the diagnosis of disease, but also can be used for the treatment of disease. Clinically, it is mainly indicated for the diagnosis of patients with encephalitis and meningitis. If subarachnoid hemorrhage is considered, lumbar puncture to extract cerebrospinal fluid for fluid release is mainly used for the treatment of the disease. The site of lumbar puncture is preferred to the 4th and 5th lumbar vertebral interspaces, and the 3rd and 4th lumbar vertebral interspaces are also available. If the 4th and 5th lumbar interspaces are selected for needle insertion, the tip of the needle should be slightly tilted at an angle of about 45 degrees between the head and the spine. If the 3rd and 4th lumbar vertebral spaces are selected, the needle should be inserted vertically. During the retention of cerebrospinal fluid, the flow rate must be slow to prevent the occurrence of cerebral hernia caused by the patient’s increased intracranial pressure. Meanwhile, after the lumbar puncture is completed, the patient must be instructed to lie flat with the pillow removed for 4-6 hours.