In this paper, the ionic conduction in the glass system AlF3-K2NbOF5 have been studied. The structure of glasses is also primarily established by Raman spectroscopy. The ionic conductivity of glasses is further discussed, based on the change of composition and structure. For glasses in system AlF3-K2NbOF5, when A1F3 content ranges from 21-26 mol%, A13+ and Nb5+ ions are in octahedral coordination, and the ionic conductivity increases with increasing AlF3 content. When A1F3 content reaches 29 mol%, A13+ ions are partly in tetrahedral coordination, and the ionic conductivity decreases. The effect is supposed to be caused by A1F4- ion tetrahedron. Because of the appearance of A1F4- ion tetrahedron, the mobile ion channels are possibly blocked. The ionic conductivity of glasses in this system is 1.045×10-2Ω-1·cm-1.at 194℃.