Carotid cavernous sinus fistula(CCSF) is an abnormal communication at the base of the skull between the internal carotid artery and the cavernous sinus. Fistula is almost associated with extensive facial trauma as a result of direct or indirect forces. Most fistulas of traumatic origin develop as a result of fractures through the base of the skull, which cause the laceration of the internal carotid artery near the cavernous sinus. The signs and symptoms of CCSF are pulsating exophthalmosis, orbital headache, pain, orbital or frontal bruit, loss of visual acuity, diplopia and ophthalmoplegia. Angiography reveals a definite CCSF and a detachable balloon embolization is known to be the treatment of choice. Even though carotid cavernous sinus fistula is an uncommon complication after orthognathic surgery, several cases of CCSF due to congenital anomalies, pre-existing aneurysms and abnormally thickened maxillary posterior wall have been reported in the literature. We have experienced a case of CCSF after Le Fort I osteotomy for maxillary advancement in skeletal class III patient and the cause, pathogenesis, diagnosis and treatment of this case.