Intracranial infection after craniotomy is one of the common and serious complications of neurosurgery, with a high rate of disability and death. Diagnostic criteria of intracranial infection: 1. Clinical symptoms and signs of intracranial infection such as high fever, headache and neck tonicity. 2. Leukocyte WBC>0.01X109/L in cerebral crest fluid examination, with predominantly increased polymorphonuclear cells. Sugar <2.25mmol/L, chloride <120mmol>0.45g/L. 3.Bacterial culture of brain crest fluid showed positive results. 4.There is a definite cause of infection, such as cerebral crest fluid leakage. Anyone with article 3 can confirm the diagnosis, such as negative bacterial culture of brain crest fluid needs to be integrated with the remaining articles. The incidence of intracranial infection after craniotomy is as high as 0.20%~27.59%, and the time of occurrence is mostly 3~7 days after surgery. The risk factors are: cerebral crest fluid leakage, extra-ventricular drainage, subclinical surgery, diabetes, nature of surgery, type of incision, timing of surgery, and time of surgery. Among them, the length of surgery time is closely related to the occurrence of intracranial infection (surgery time >4 hours increases the risk of intracranial infection by 2 times). Therefore, shortening the operation time, tight suturing to prevent cerebral crest fluid leakage, and minimizing the placement of various drains or shortening the placement time play an important role in reducing intracranial infections after neurosurgical craniotomy. But here the ventricular drainage tube is also an exception, and he is a double-edged sword. The Expert Consensus on the diagnosis and treatment of infection in critically ill neurosurgical patients in China (2017) states the principles of antimicrobial treatment for neurosurgical CNS infections: when a central infection is suspected, the relevant specimen should be retained for bacterial smear or culture and then empirical antimicrobial drug therapy should be started promptly; selection of antimicrobial drugs that can easily cross the blood-brain barrier is recommended as the preferred bactericidal agent, and the treatment route is recommended to be the intravenous route; empirical antimicrobial drug If the treatment is not effective for >72 h, consider adjusting the treatment plan (intravenous combined with intracerebroventricular or intrathecal in clinical practice). The intracerebroventricular drug here is the intracerebroventricular drug treatment through the extraventricular drainage, at the same time, the extraventricular drainage can also play the purpose of drainage of “dirty” brain crest fluid, so how to use this “tube” well, for the treatment of intracranial infection, is crucial.