100 patients with destruction of skull base in nasopharyngeal carcinoma, confirmed by pathology and CT scanning before radiotherapy, were analysed. It showed that the primary characteristics of skull base destruction are headache and cranial nerve involvement. Although the destruction of skull base showed evident manifestation in TNM classification, it can be inferred that the erosion development probably took place within 1-6 months. Comparing the CT scanning with X-ray submento-vertical view, the result indicated that the erosions of the various positions of the skull base and the invasion of paranasal sinus, cavernous sinus and orbit were clearly displayed by CT scanning but only 23% was discovered by X-ray. There was significant difference between CT scanning and X-ray, and CT scanning had more advantages. The relation between the erosion of the skull base and the invasion of parapharynx space and the metastatics of the cervical nodes were also discussed.