Poly（lactic acid）/montmorillonite nanocomposites were prepared by the melt inter calation method. Their structures and thermal properties were investigated by WA XD, DSC and TGA techniques. The WAXD results show that the interlayer spacin g of montmorillonite in the nanocomposites was increased after melt intercalat ion, indicating that the molecular chains of poly（lactic acid） had been interc alated into the montmo-rillonite layers. The thermal stability of poly（lact ic acid） was obviously improved after intercalation with montmorillonite. Compar ed with that of pure poly（lactic acid）, the thermal decomposition temperatures o f the nanocomposites were increased by about 22.5 ℃ in air and 14 ℃ in N2 , respectively.
