Sphere indentation stress strain relation and contact damage for pure brittle and quasi bri ttle materials were investigated using steel spheres with different sizes as the indenter. Elastic modulus and the critical stress to cause damage were determined on the base of linear elastic relationship between the load and the contact area. It was demonstrated that the indentation method is available and convenient for nondestructive evaluation and in situ testing of brittle components, especially for concrete structure. Experiments with different concrete specimens and glass were performed, and corresponding young's modulus was obtained. A small and simple device for in situ test was designed and machined.