Objective To provide the endoscopic anatomic basis and anatomic parameters for endoscopic surgical therapy on orbital lesions , and to analyze the advantages and key points of this surgical approach .Methods Five fresh adult heads were used in this experiment .Endonasal thanslamina approach and endoscopic technique were applied to observe important anatomic marks while intraoperative medicalization of the medical rectus muscle was applied to observe the exposure and positioning of important structures and trends of the optic canal and intra orbit .Results Uncinate process was at the lower front corner of middle nasal concha; ethmoidalis bulla was behind the uncinate process , and ethmoidei sinus was reachable after an incision was made on ethmoidalis bulla;anterior ethmoidal artery and posterior ethmoidal artery were the important anatomic landmarks of the inner ethmoidei sinus;optic canal prominence , carotid artery prominence and OCR were the important anatomic landmarks of the inner sphenoid sinus; lamina papyracea was at the lateral wall of ethmoidei sinus , and orbital contents were approacchable after lamina papyracea was cut off ;inside orbit , the optic nerve was approachable through the gap between the medial rectus muscle and inferior rectus muscle .The ophthalmic artery of 9 out of 10 sides of the specimens was originated from the supraclinoidal segment of the internal carotid artery while the remaining one was originated from the cavernous segment of internal carotid artery .There were 7 sides in which ophthalmic artery was located at the inferior lateral of the optic nerve;there were 2 sides in which ophthalmic artery was located at the inferior of the optic nerve; the remaining one was located at the inferior medial of the optic nerve .Conclusion The endoscopic endonasal thanslamina approach can sufficiently expose the optic nerve and the structures in the medical space of the orbit.Uncinate process, ethmoid bulla, anterior ethmoidal artery, posterior ethmoidal artery and posterior ethmoid sinus are the important landmarks of the endoscopic endonasal thanslamina approach .Optic canal prominence , internal carotid artery prominence and OCR are the important landmarks for optic canal decompression .Ophthalmic artery , orbital branches , anterior ethmoidal artery , posterior ethmoidal artery , internal carotid artery are the important vessels . Medialization of the medial rectus muscle is effective to approach the orbital anatomical structures .