Objective To provide detailed anatomical data for endoscopic surgery by studying the related anatomy of the pterygopalatine segment of internal maxillary artery (PSIMA) and its surrounding area through transnasal endoscopic approach. Methods In 10 fresh cadaveric heads (20 sides), the pterygopalatine fossa (PPF) was observed via transnasal endoscopic approach. After the heads were split, the important bony symbols of PPF, the neurovascular structure and their relations with the surrounding structures were observed via median sagittal approach. Results ① The branch patterns of the PSIMA varied prodigiously. Of all the sides, the PSIMA was emitted sequentially in 5 (25%), originated from the common stake of inferior ophthalmic artery (IOA) and posterior superior alveolar artery in 10 (50%), and emitted respectively from internal maxillary artery (IMA) in 8 (40%). The ratio of simultaneous emittence of IOA, descending palatine artery (DPA), sphenopalatine artery (SPA) from IMA was 10% (2 /20). IOA and DPA were emitted in a common stake in 10% (2/20). The ratios of emittence of pterygoid canal artery and foramen rotundum artery from IMA separately and with a common stake were 50%(10/20) respectively. ② Transnasal endoscopic approach could preferably manage IMA and its branches with little disturbance to the surrounding structures. Conclusion Being familiar with the anatomy of PSIMA and its surrounding regions can reduce complications of intranasal endoscopic surgery, therefore has important significance in the treatment of intractable epistaxia and transnasal endoscopic surgery of maxillary peterygopalatine fossa.