With the development of endoscopic technique, Caldwell–Luc approach has more wide applications and becomes a common method of pterygopalatine fossa (PPF) surgery. Few data can be used in this approach to avoid injuring the vessels and nerves within this area. In this study, the authors used computed tomography to get the coordinates of inferior orbital fissure, foramen rotundum, sphenopalatine foramen, internal opening of pterygoid canal, the strangulation of PPF, and the greater palatine foramen with canine fossa as the origin. Parameters of 60 patients (120 observations) between 35 and 55 years who have no experience of trauma or surgery before were involved in this study. The data were analyzed by SPSS, statistical software with the comparison between sexes and sides. After calculating the relative distances and angles between these points and canine fossa, the authors get the proportions of the upper part of PPF, and the pterygopalatine canal to PPF, respectively. The authors finally got the safety surgical range. The results are meaningful to safety in surgery and complication avoidance, which can be great references in clinical applications.