The failure stress of two kinds of alumina with six different notch radii were tested. Statistical analysis of the fracture strength indicates that although the fracture strength of smooth specimens conforms to a Weibull distribution, the fracture strength of notched specimen conforms to a normal distribution. The test results show that fracture toughness of structural ceramics also conforms to normal distribution.Therefore the normal distribution will be adopted as reliability design is applied to structural ceramics.