Digital image correlation (DIC) is a non-contact optical method, which can be widely applied to characterization of mechanical behavior of biological materials. This paper described the basic processes of this method in determining the displacement and strain components. Three applications were presented to illustrate how this technique was applied. The first application was to evaluate the mechanical behavior of the bovine artery (soft tissue). The second was to identify the fracture toughness of human dentin (hard tissue). The last was an example to measure shrinkage strain of human dentin at microscopic scale.