Abstract: Emulsion polymerization was adopted in the preparation of P（BA-AA）/organically modified nano montmorillonite (nano-OMMT) composite. X-ray diffraction (XRD) and fourier transform infrared spectrometry (FTIR) were used to characterize the structures of the composites. The thermal stability was examined by thermogravimetric analysis (TGA)，and mechanical properties of the composites were also tested. When monomer ratio BA-AA was 3：2，partially intercalated and partially exfoliated nanocomposite was obtained. Adding 3%~7% nano-OMMT can significantly improve thermal stability of the composites. When the nano-OMMT mass fraction was 7%，its thermal stability was the highest. The addition of nano-OMMT effectively improved the tensile strength of the composites.

Key words: emulsion intercalation polymerization, butyl acrylate-acrylic acid copolymer, nano-OMMT, composite, thermal stability, mechanical property