Some oxygen-containing groups (mainly C=O group) are introduced on the molecular chain of HDPE during electron beam irradiation in air. The affinity between HDPE and sericite-tridymite-cristobabite (STC), the dispersion of STC in HDPE matrix are improved owing to the polar groups introduced. By treating STC with amino-containing silane coupling agent, the interfacial adhesion between irradiated HDPE (e-HDPE) and treated STC (t-STC) is further improved, the mechanical properties of e-HDPE/t-STC blend are improved quite a lot. The experimental results show that due to the improvement of interfacial interaction, the interfacial phase can transmit the stress subjected to the HDPE matrix and make the matrix absorb energy by plastic yield or deformation; the impact strength of e-HDPE/t-STC blend is thus improved.