Objective To observe the anatomical characteristics of the parapharyngeal space via endoscopy-assisted transoral approach. 

 Methods The dissection was performed on 5 fresh cadaver heads(10 sides),and the structure of the lateral pharyngeal space was observed via endoscopy-assisted transoral approach.  Results The superior constrictor muscle and the musculus medial pterygoid were the landmarks of the prestyloid space．Otherwise the critical marks which divided the parapharyngeal space into 2 parts were stylopharyngeus and styloglossus muscles．The internal carotid artery, the internal jugular vein and the posterior cranial nerves were laterally to the superior constrictor muscle，and meanwhile posterior to the stylopharyngeus and styloglossus muscles．The horizontal distances from the styloid process tip to the glossopharyngeal nerve, hypoglossal nerve and vagus nerve were measured as follows, respectively（3.05±0.08）mm（2.94-3.14 mm）,（2.94±0.04）mm（2.44-2.56 mm）,（1.50±0.03）mm（1.46-1.56 mm）; with the pharyngeal muscle of styloid process as the standard the result  showed that the glossopharyngeal nerve was close to the inner side of the muscle and the horizontal distance of hypoglossal nerve and vagus nerve were respectively（3.00±0.03）mm（2.96-3.04 mm）and（5.99±0.03）mm（5.94-6.04 mm）. During the anatomy, the accessry nerve was far away from styloid process and styloid process pharyngeal muscle, which could hardly be touched and measured during the operation.  Conclusion The parapharyngeal space can be well exposed by endoscopicassisted transoral approach. The superior pharyngeal constrictor muscle, internal pterygoid muscle, stylopharyngeus and styloglossus muscles are essential landmarks in tumor resection of the pharyngeal space via transoral approach．