Composites of high density polyethylene (HDPE) filled with Na-MMT modified with aminopropyltriethoxysilane (-APTES) in the presence and absence of HDPE grafted maleic anhydride (HDPE-g-MA) were prepared. The composites were processed via melt mixing technique in a Brabender internal mixer. The operation conditions were 180 °C and 60 RPM for 15 minutes mixing process. XRD test was carried out to investigate the gallery distance of silane modified clay in the bulk of HDPE matrix. TEM microscopy was carried out to observe the dispersion and distribution of silane modified nanoclays inside the bulk of HDPE matrix. Silane modified clay had a better intercalation in the presence of HDPE-g-MA compatibilizer which could be due to the formation of chemical bonds between amine end groups of -APTES and anhydride groups in the compatibilizer. DSC analysis was carried out to study the effect of silane modified nanoclays on crystallization of HDPE matrix.