In this article, poly(acrylonitrile-co-methylacrylate)/attapulgite (AT) nanocomposites have been prepared by mechanical blending. The hydrogen bonding (H-bonding) behavior between the copolymer and unmodified AT were investigated by Fourier Transform Infrared. The results indicated that the H-bond index (HBI) decreased with increasing AT content. According to the dynamic mechanical analysis, the storage modulus and heat distortion temperature of the nanocomposites gradually increased with increasing AT content while the glass transition temperature reached the maximum when AT content was 1 wt%. X-ray diffraction results demonstrated that the sample with the highest HBI value had the lowest crystallinity, suggesting the H-bond interaction restricted the motion of polymer chains, thus decreased crystallinity of the nanocomposites. POLYM. ENG. SCI., 50:312-319, 2010. (C) 2009 Society of Plastics Engineers