In this study, the morphological, rheological, and mechanical properties of PP/HDPE blend compatibilized with poly (propylene-g-maleic anhydride) were studied. Necessary blends were prepared using a counter current twin-screw extruder. The blend composition ranged from 10 to 50 wt% of dispersed phase (HDPE) and compatibilizer (MAPP) with two Concentration ranges 10, 20 wt% were used for PP/HDPE (80/20) blend with respect to the dispersed phase (HDPE). The results of morphological studies shows a droplet dispersion morphology in the composition to 50wt% HDPE content, which indicates that HDPE forms a dispersed phase and PP forms a continuous phase in these composition region. Addition of the MAPP compatibilizer decreases the dispersed phase diameter. Rheological studies show that addition of the MAPP compatibilizer increases the melt viscosity, complex viscosity, storage, and loss modulus of the blends. Mechanical studies show that with increasing of HDPE concentration the tensile and impact strength first increase, and then decrease. The elongation at break decreases with increasing of HDPE concentration. Addition of the MAPP compatibilizer increases the elongation at break, tensile, and impact strength.