Close to 20% of meningiomas are non-benign and are prone to tumor recurrence after surgery. Even the other 80% of benign meningiomas may develop tumor recurrence several years after surgery. Depending on the size of the tumor, recurrent meningiomas found when the tumor is relatively small in size can be treated with Gamma Knife to control the growth of the tumor, but if the tumor is already relatively large in size, the only option is to remove it surgically again. Then, can meningioma become malignant after recurrence? This question needs to be answered by the pathological classification and malignancy of meningioma. Meningioma is classified as Grade I, II and III according to the standard of World Health Organization, where Grade I is benign, Grade III is malignant and Grade II is in between. If the first malignant meningioma is grade III, the grade or malignancy of the tumor will not decrease after recurrence, but since grade III is the highest grade of meningioma, grade III meningioma is still grade III after recurrence, and the grade will not increase. However, since Grade 3 is the highest grade of meningioma, Grade 3 meningioma will still be Grade 3 after recurrence and will not increase in grade. Dr. Ke Chao’s team at the Cancer Hospital of Sun Yat-sen University followed up 845 cases of meningiomas operated in their hospital and compared the pathological diagnosis of meningiomas operated again after recurrence with the pathological diagnosis of the first time, and found that meningiomas of grade 2 can become malignant after recurrence and become meningiomas of grade 3 with higher malignancy, but this is only a relatively small percentage of meningiomas of grade 2. Most grade II meningiomas remain grade II even after multiple recurrences. A certain percentage of benign grade 1 meningiomas recur several years after surgery. Some recurrences grow after Gamma Knife treatment and then opt for surgery, while others are found to be larger and opt for surgery again. A small percentage of benign grade 1 meningiomas are found to be malignant after recurrence, with some progressing from benign grade 1 to grade 2, and some even progressing from benign grade 1 to malignant grade 3. From the follow-up and summary of these meningioma cases, we can find that most of the meningioma recurrences are of the same grade as before, but a small percentage can progress to a more malignant and higher grade meningioma.