With the widespread development of microsurgery and the advent of equipment and surgical instruments, and the increasing experience of physicians, more and more surgeries are being performed for gliomas in important functional areas. For example, intraoperative MRI, intraoperative ultrasound, intraoperative neurophysiological monitoring and intraoperative wake-up anesthesia facilitate the removal of tumors in functional areas with minimal impact on neurological function, and in addition, preoperative PET-CT and special imaging of MRI facilitate the removal of gliomas in functional areas. In addition, brainstem glioma has always been considered inoperable because it is an important life center of human body, and the risk of surgery is extremely high, so it used to be considered a forbidden area for brain surgery. The prognosis of some patients is also good. However, if the tumor is deep in the brainstem and relatively small, surgical resection will cause more damage to the brainstem and may result in serious complications and even threaten the life of the patient. Is it true that the more malignant the tumor is, the more the tumor should be cut cleanly? In principle, the cleaner the glioma, the better. However, in some cases, there are limitations, especially for malignant gliomas, especially glioblastoma, where studies have shown that tumor cells can be detected in the outer 5 cm of the local lesion, so it is simply impossible to achieve a complete tumor excision. Forced total excision will cause permanent neurological dysfunction and even life threatening consequences to the patient. Of course, for tumors in non-functional areas, they can be moderately enlarged and resected without affecting the patient’s function. For glioma without obvious demarcation from surrounding nerve tissue, how to cut it? Nowadays, all intracranial tumors are microsurgery. Through microscope and combined with intraoperative MRI, ultrasound, neurophysiology and other examination equipment, the tumor can be separated and removed along the cerebral sulcus and nerve fiber bundle, which can make minimize the neurological function damage. Can we determine whether the tumor is ready for total excision before surgery? Will there be any changes during the surgery? Pre-operative evaluation is done to determine the location and grade of the tumor in conjunction with the imaging data to determine the surgical plan. If the tumor is relatively in the non-functional area and the tumor grade is low, it is expected to be able to achieve total resection of the tumor; if the tumor is in the important functional area with deeper location and higher grade, then total resection is very difficult and can only be done to the maximum extent with safety.