Polyamides are widely used thermoplastic polymers having good mechanical, electrical and chemical properties. Synthesis of polyamides is based on the condensation polymerization using diamines and diacids as monomers. The use of different types of monomers enables to get polyamides with special properties. Polyamide 66 (Nylon 66) is a semi-crystalline thermoplastic polymer having higher melting point than other polyamides. Moreover, it maintains its stiffness with increasing temperature. It has low friction coefficient, high stiffness, wide color options, high toughness, creep resistance, flame retardant, electrical insulation, abrasion resistance, external condition resistance and easy operation properties. Recently, their mechanical properties have been improved with glass fibers with different size and feeding ratio. Polyphthalamides are semi-aromatic and semi-crystalline thermoplastic polymers having high heat resistance. They can be used in chemical or high temperature conditions because of their good thermal resistance and low moisture absorption. They are usually mixed with aliphatic polyamides to prepare their blends providing higher mechanical properties and lower densities. When the aromatic polyamides and aliphatic polyamides are mixed, the processability of aromatic polyamides are improved. In this study, the compability of polyphthalamide and polyamide 66 blends reinforced with 50% glass fiber is investigated by different feeding ratio. During constant glass fibre ratio, polyphthalamide and polyamide blends are prepared by different feeding ratio using extrusion. Finally, test samples are prepared by injection molding method. The effects of feeding ratio of polymers on the mechanical and thermal properties are studied by thermal and mechanical tests.