In this work, nanocomposites based on LLDPE, clay-APS without and in presence of PE-g-AM were prepared by blending in melt state in the Haake internal mixer. Afterwards, the products of the mixing were pressed by the Toyoseiky press at 180°C during 3 minutes under pressure from 150 to 220 kg/cm2. The XRD and TEM images showed that the LLDPE/3 percent clay-APS nanocomposite was in intercalated form, in which the starting basic spacing of clay-APS increased from 1.92 nm to 3.24 nm. But the LLDPE/l0 percent PE-g-AM/3 percent clay-APS nanocomposite had the exfoliated form: the peak corresponded to the starting basic spacing at 4.5° was disappeared and the clay-APS layers were exfoliated in LLDPE-matrix. The mechanical properties of nanocomposites were increased due to the good compatibility and the good interaction between LLDPE, PE-g-AM and clay-APS. The thermal properties of nanocomposites were considerably ameliorated because of the barrier effect of clay-APS layers.