A glass-fiber, grafted by hyperbranched polymer with hydroxyl group (GF-HBPH), reinforced epoxy-based composite was evaluated for mechanical properties and compared with the neat epoxy and silanized glass-fiber, GF-APS. The epoxy/GF-HBPH composites were studied by attenuated total internal reflectance infrared spectroscopy, 1 H nuclear magnetic resonance spectroscopy, thermal gravimetric analysis, mechanical properties analysis, and field emission-scanning electron microscopy. The results showed that the incorporation of GF-HBPH could simultaneously enhance the mechanical properties of the epoxy composites. Field emission-scanning electron microscopy images of the fracture surfaces of the test specimens were used to support the results and conclusions.