Abstract: How to evaluate the brittleness of quasibrittle material has been a focus of attention in material science for years.However,there is a remarkable shortcoming for the most available brittleness indexes that they are influenced distinctly by size of testing sample.So they are not material property but material behavior.Based on size effect law proposed by Bazant,the intersection point of the asymptote of size effect curve and the fracture process zone length are suggested to reflect the brittleness of materials.The indexes can be used widely for quasibrittle material because it can be achieved easily and exactly.