The effect of SiO2 on the sintering rate of YSZ ceramics as well as on the morphology and properties of YSZ during sintering are studied. In this work, YSZ samples of 10% pores with different SiO2 content were prepared. The sample microstructures are characterized by scanning electron microscopy (SEM). The sample porosity was obtained by the Archimedes method. The phase composition, mechanical and thermal properties of samples after sintering were measured. It is found that the introduction of 0.3wt% SiO2 will make the YSZ grain size larger and the porosity decrease significantly. The hardness, Young's modulus and thermal conductivity of samples change faster due to the introduction of SiO2.