Objective 64-slice spiral CT was applied to research internal auditory canal and the surrounding structures. To provide important information for preoperative evaluation of acoustic neuroma and to predjct the operative pmcedures. Methods 30 cases with acoustic neuroma underwent the thin CT scanning of the skull base. To observe the form of internal auditory canal, mastoid air cells and jugular bulbin in acoustic neuroma. Results Internal auditory canal of acoustic neuroma were divided into three forms:trumpet(n:22, 73.3.0％), ampulla(n=6, 20.0％)and irregular(n=2, 6.7%). Due to the large internal auditory canal,the posterior wall of internal auditory canal were not removed and the tumor were directly removed through the drawing in 1 case of irregular and 3 cases of ampulla. The posterior walls of internal auditory canal were removed in 19 cases of trumpet, 6 cases of ampulla and 1 case of irregular.3 cases complicated with high jugular bulb. High speed steel cutting drill was used to drill the posterior walls of internal auditory canal as close as possible to the inner rear wall and as shorter as possible ,to prevent jugular bulb bleeding. 2 cases showed good gasification mastoid. Mastoid air cells were opened during the surgery and were closed immediately, having slight leakage of cerebrospinal fluid after surgery. Conclusion Thin CT scanning of the skull base should be done routinely for preoperative assessment of acoustic neuroma. Because it is helpful to the appropriate management of the posterior wall of internal auditory canal.All of these can improve surgical resection and reduce the trauma to the patient.