Recently, a lot of researches are directed to recycling of waste materials such as waste tires and marble and granite dust (GM). The management of solid wastes is essential to prevent the harmful effects and hazards associated by the contamination of these wastes. Waste tire rubber particles (WTRP) are added to high density polyethylene (HDPE) matrix to increase the impact strength of HDPE, while it results in the decrease of other mechanical properties. GM is added to this mixture to modify some mechanical properties such as hardness and compressive strength, this mixture results in a novel hybrid composite. The effect of using different GM wt.% on different mechanical properties of the composite is studied. Mechanical testing such as three-point bending, Charpy impact, compression and shore D hardness is implemented according to ASTM standards and Scanning electron microscopy examination of the microstructure of WTRP-HDPE-GM hybrid composite is used to support the explanation of the results.