In this study, an epoxy (bisphenol-A type) was selected as a reactive compatibilizer for enhancing the compatibility of immiscible blends of polyamide6(PA6) and poly(ethylene terephthalate)(PET). These blends possess highly desirable qualities, such as low cost and increased moisture absorption, and can be used to construct practical polymer alloys. Using epoxy as a reactive compatibilizing agent, the compatible blends of PA6/PET/epoxy were successfully prepared through melt compounding using a twin-screw extruder. The domain size of PET decreased by a factor of two in the PA6 matrix with the epoxy. The effect of the epoxy on the melt viscosity, crystallization, and tensile properties of the blends indicates that the high-molecular weight epoxy can be an effective compatibilizer in PA6/PET blends.