Objective: To explore quantitatively microsurgical anatomy in sellar region via the transpterional keyhole approach assisted by neuro-navigation. Methods: 15 silicone-injected adult cadaveric heads were dissected under operating microscope. The microstructures of sellar region were observed. The parameters of spaces ofⅠ,Ⅱ,Ⅲ,Ⅳ andⅤwere quantified by neuro-navigation. Results: The transpterional keyhole approach could expose five spaces very clearly. The areas of Ⅰ,Ⅱ,Ⅲ,Ⅳ and Ⅴspaces were （22.23±2.12）mm²,（63.42±7.84） mm², （64.96±5.43） mm²,（26±5.85 ）mm², and（16.64±2.97 ）mm² respectively.  Bilateral optic nerve, optic chiasma, sellae diaphragma and stalk hypophysial, and controlateral internal carotid artery, ophthalmic artery and superior hypophysial artery were well observed. Transpterional keyhole approach was more advantageous to view the Ⅱ、Ⅲ andⅤspace, especially  the  exposure for PcoA and AchA. The bifurcation of A1、M1 and the course of oculomotornerve in cistern could be well observed through the Ⅱ、Ⅲ andⅤ space. Conclusions: The transpterional keyhole approach could well expose the interspaces in sellar region, which is reliable to view sellar and parasellar structures  through the Ⅱ、Ⅲ andⅤspace, as well the exposure of the origin and branches of PcoA and AchA.