Abstract: Epoxy resin composites filled with high-alumina fly ash cenospheres were prepared in this paper. Their impact strength and erosive wear behaviors were investigated by impact test and erosive wear test. Polyamide 650 was determined as an ideal curing agent to epoxy resin according to the erosion wear mechanism, wear resistance and impact performance. Silane coupling agent improves the compatibility of the cenospheres and the epoxy resin matrix, which effectively increases the erosion resistance of the composites. When the mass fraction of the cenospheres is less than 3%, the impact strength and the erosion resistance of the composites does not change obviously. When the mass fraction of the cenospheres is 3%, the impact strength reaches maximum and the erosion resistance also increases obviously. And when the mass fraction of the cenospheres is 4%, the erosion resistance is the best. As a result, the appropriate mass fraction of high-alumina cenospheres was determined ultimately to be 3% to 4%.