Abstract: The reinforced high-density polyethylene (HDPE)/bamboo flour (BF) composites were prepared by melt blending using maleic anhydride grafted HDPE (HDPE-g-MAH) as a compatibilizer and glass fiber (GF) as a reinforcing filler. In order to improve the interfacial adhesion between GF and HDPE and the dispersion of GF in the matrix, a silane coupling agent 3-methacryloxypropyltrimethoxysilane(KH570)with unsaturated double bonds was used to modify GF. Moreover, dicumyl peroxide (DCP) was used to initiate the grafting reaction between the double bonds in KH570 and HDPE. The modified GF was characterized by Fourier transform infrared spectroscopy (FT-IR) and energy dispersive spectroscopy (EDS), and the morphology and properties of HDPE/BF composites reinforced by GF were characterized by scanning electron microscopy (SEM), mechanical testing, Vicat softening temperature (T_VS) measurement and thermogravimetric (TG) analysis. Results indicate that KH570 modification can improve the interfacial adhesion and the dispersion of GF, resulting in great improvement of the mechanical properties of the composite, and the impact strength, flexural strength and flexural modulus of the HDPE/BF composite (m(GF-KH570):m(HDPE/BF)=10%) are increased by 48%, 21% and 25%, respectively, compared with HDPE/BF composite. The interfacial interaction between GF-KH570 and the matrix can be further enhanced by the chemical bonding resulting from the grafting reaction initiated by DCP, thus the resultant composite exhibits excellent balance properties, and the impact strength, flexural strength and flexural modulus of the resultant HDPE/BF composite is increased by 69%, 40% and 43%, respectively, compared with the corresponding HDPE/BF composite.