Zirconia soild electrolytes containing 4~10mol% of yttria were prepared by wet-blending of oxides and rea-ction-sintering, Sinterbility and degree of stabilization were optimized for the development of oxygen sensor. Fracture strength thermal expansion coefficient electrical conductivity and galvanic potential were measured and discussed with respect to the amount of ytria addition phase transformation microstructure and degree of stabilization. It was found that sintering and stabilization occurred when the composition was designed to be near the boundary region of $ZrO_2-Y_2O_3$ binary system. In such away a good zirconia solid electrolyte suitable for oxygen sensor could be developed.