Yttria-stabilized zirconia(YSZ)/Al2O3 composite materials were prepared by mechanically mixing, dry pressing and high temperature sintering of YSZ with Al2O3 and Al(NO3)3 as aluminum sources, respectively. The effects of aluminum sources and addition amounts on the sinterability, electrical conductivity and mechanical property of YSZ/Al2O3 composites were investigated by means of scanning electron microscopy, electrochemical impedance spectroscopy and three-point bending test. The results show that addition of suitable amounts of Al2O3 or Al(NO3)3 into YSZ can promote the sinterability of YSZ and improve its electrical conductivity and flexural strength. Sinterability and electrical conductivity of YSZ/Al2O3 composites using Al2O3 as aluminum source are higher than those of using Al(NO3)3, but mechanical strengths exhibit the contrary trend at the same addition amount. When 0.5 wt.% of Al2O3 is added into YSZ, the relative density of 98.8% and the electrical conductivity of 0.0703 S·cm-1 at 800 ℃ are achieved on YSZ/Al2O3 composite electrolyte sintered at 1350 ℃ for 10 h. The electrolyte-supported unit cell constructed by the YSZ/Al2O3 composite electrolyte gives the maximum power density of 308 mW·cm-2 at 800 ℃ using H2 as the fuel, which is higher than that of the pure YSZ electrolyte and exhibits good stability.