The electrical and mechanical properties of the 8 mol% yittria-stabilized zirconia and alumina composites have been examined as a function of the alumina content. The 3-point bending strength and fracture toughness of the composites increased with increasing alumina content up to 20 wt%. The average grain size of the composites decreased with increasing alumina content up to 20 wt%. The composite with 5 wt% $Al_2O_3$ showed a 3-point bending strength of 310 MPa and fracture toughness about $7.8MPacdot extrm m^{1/2}$. The electrical conductivity of the composites at $1000^{circ}C$ increased slightly with increasing alumina content up to 10 wt% and decreased monotonically with alumina content. The conductivity of the TZ-8YS with 5 wt% alumina was 0.4 S/cm at $1000^{circ}C$.