Intercalation of PEO in Na-MMT and sa-MMT are accomplished bY heating the polymer with the host at 80℃. The X-ray diffraction pattern before any heating contains peaks characteristic of both pristine silicate(d=12.3A＾˚) and crystilline PEO(d=4.5, 3.8 and 3.1A＾˚). After heating to 80℃, in case of using Na-MMT, the d-spacing of pristine silicate was increased from 12.3 to 18.2A＾˚, and the peaks of crystalline PEO was reduced. These results indicate that PEO was intercalated into Na-MMT. But, in use of sa-MMT, the intercalated nanocomposites were not obtained. And these results of molecular weight effect on intercalation of PEO in Na-MMT, PEO were easily intercalated as the molecular weight decreased.