Rock mass is a multi-fractured body. Regardless of the size of these flaws, they can reduce the strength of rock materials . As rock is not a transparent material, the process of deformation to failure is difficult to observe. Transparent brittle materials are able to solve this problem. This paper provides a production method of prefabricated defects. And the results prove that the frozen PMMA and glass are very similar with rocks in breaking process and mechanical properties.