Abstract: The thermal shock resistance of coating was increased by adding SiO₂ to the stable ZrO₂+8%Y₂O₃ layer due to the difference of thermal expansion coefficient between SiO₂ and ZrO₂,which facilitated the formation of reticular microcracks and increased the density of the microcracks,as well as the elastic module of the coating was decreased and the internal stress in coating layer was released,too.The experimental results show that optimum amounts of SiO₂ were 3wt%.When excessive SiO₂ was added,the big cave could formed,which facilitated microcracks expending and fracture,as well as the thermal shock resistance of the coating was damaged,too.