The development of polymeric nanocomposites has invoked much interest in recent years. These nanofillers have great affect on the mechanical, barrier, electrical and thermal properties of base polymers. The present study aims to develop HDPE matrix composite reinforced with silica sand nanoparticles. The silica sand nanoparticles with average particle size of less than 100nm was produced by several stages of ball mill and heating combinations. HDPE matrix composites with 5, 10, 15 and 20 wt. of silica sand nanoparticles were developed through internal mixing of silica sand nanoparticles with HDPE and then using compression moulding machine. Physical properties, mechanical behaviour, thermal behaviour and microstructure were studied. It was observed that physical properties increased with increasing trend of silica sand nanoparticles in HDPE. Mechanical properties increased with an optimum value of 15 wt. of silica sand nanoparticles in HDPE. DSC analysis shows a reduction in degree of crystallinity of the composites with increasing trend of silica sand nanoparticles. © 2011 IEEE.