Abstract: The combination of the high density polyethylene (HDPE) with variable amounts of the organoclay for investigating the mechanical, thermal and chemical properties of the synthesized nanocomposites were prepared. The effects of the addition of polyethylene glycol (PEG) as a compatibilizer into the polymer matrix on these properties were regarded. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) for estimating the morphology study of the nanocomposites were provided. Tensile strength, Young`s modulus, surface hardness, Thermogravimetric analysis and adsorption resistant tests of all compounds for mechanical, thermal and chemical investigation were prepared. The morphology studies indicate that the addition of PEG has remarkably improved the dispersion of clay into the matrix. The most efficient amount of organoclay into the resin for enhancing the mechanical properties was obtained at about 5 wt. %. The results reveal that the thermal stability of nanocomposites enhanced with adding the organoclay and this property has been deteriorated without any compatibilizer. The adsorption resistant of samples decreased against the rising of the clay content into the polymer matrix.