Abstract: The effect of adding nano γ-Al₂O₃ powder on the sintering characteristics and microstructure of alumina and silicon carbide fibers was investigated. The results showed that the nano γ-Al₂O₃ powder was stuffed into the pores formed from the packing of micron alumina powder when its fiber was extruded. The density of the green alumina fiber increased with addition of nano γ-Al₂O₃ powder. The maximum density of the green fiber was obtained when γ-Al₂O₃ content is approximately 40%. Nano γ-Al₂O₃ powder, can promote the sintering of alumina and silicon carbide fibers, and a lower sintering temperature and higher fiber density may be expected.