Digital image correlation (DIC) is a non-contact, full-field optical measurement method .DIC was used to research the compression damage of concrete. Black and white paints were sprayed on the specimen’s surface to artificially make random speckles. Images during loading process were captured by high resolution CMOS. An open 2D-DIC system developed by MATLAB and C++ was used to get full-field displacement of the specimen surface. The results show that the displacement catastrophes always appear before compression failure, which can be inspected by DIC method. Effective corr-coef cutoff have to be set to remove those invalid points with low-level of correlation so that we can eventually get the real shape, length as well as the width of the crack on the specimen surface. This result can be useful on other studies on damage principle of concrete like finite-element analysis.