F-montmorillonite (F-MMT) was synthesized by a hydrothermal method at 493 K for 72 h, in which a little of hydroxyl radical is replaced by fluoride ion in the silicate structure. Poly(vinyl alcohol) (PVA)/F-MMT nanocomposites were prepared using the synthetic F-MMT by a solution-intercalation method. The F-MMT and PVA/ F-MMT nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results indicate that the flake structured F-MMT is homogeneously dispersed in PVA, forming an exfoliated nanocomposite structure. Thermogravimetric analysis, mechanical performance and UV-visible spectroscopy were applied to test the properties of PVA nanocomposites, which indicate that the thermal stability and mechanical performance are enhanced distinctly, without a sacrifice in optical clarity. The improvement of mechanical and thermal properties was attributed to the homogeneous and good dispersion of F-MMT in polymeric matrix and the strong hydrogen bonding between O-H of PVA and F -of F-MMT.