The clinical efficacy of polymyxins in severe infection caused by carbapenem resistant organism (CRO) has gradually been recognized, and the course of treatment is generally 2 to 4 weeks. The most common complications after intravenous injection are nephrotoxicity and neurotoxicity, however, there are few reports on the efficacy and safety of the long course use of polymyxins. A patient with carbapenem resistant Acinetobacter baumannii (CRAB) infection after neurosurgery was admitted to the department of neurosurgical intensive care unit (NICU) of Lanzhou University Second Hospital. As the family refused the excision of brain abscess and Ommaya reservoir placement, polymyxin B was given intravenous (3.0 mg·kg -1·d -1) combined with intrathecal (5 mg once daily) injection, and high-dose sulbactam (8 g/d) was intravenously injected for anti-infection therapy. Finally, the brain abscess was absorbed and the patient was successfully cured. The total course of polymyxin B was 69 days with a cumulative dosage of 7 500 mg. There were no complications such as polymyxin-related nephrotoxicity and neurotoxicity during the period, and no symptoms of respiratory inhibition or neuromuscular blockage were observed, but polymyxin-related skin pigmentation appeared about 1 month after intravenous administration of polymyxins B, which subsided after drug withdrawal. It is suggested that long course of polymyxins B is safe and effective for intracranial infection caused by CRAB.