In this paper, the preparation and compare of some mechanical and physical properties of two groups of polymer blends consisting of polyvinyl chloride with polypropylene (PP-PVC) and poly-vinyl chloride with high-density polyethylene (HDPE-PVC). Using a twin-screw extruder, three weight percentages of PP and HDPE (5, 10 and 15%) were used to prepare the polymer blends. Experimental investigation was carried out for analyzing the mechanical properties liketensile strength, flexural strength, compression, impact, and hardnessand physical properties (thermal characteristics and melt flow index) for the polymer blend samples. The results show that the polymer blend (HDPE-PVC) get higher values than polymer blend (PP-PVC) in fracture strength, young´s modulus, elongation, flexural strength, creep resistantand maximum shear stress and thermal characteristics, whereas the polymer blends (PP-PVC) get higher values in impact strength, fracture toughness, hardnessand compression and melt flow index. Besides, the increment in PP or HDPE content weak the properties of the polymer blends and the samples with (5%PP:95%PVC) and (5%HDPE:95%PVC)were the best among the other polymer blends samples.