The measurement of crack propagation in solids is of vital importance for the research of the fatigue characteristic of solid materials. By analysis of the image based measurement technique, a contact-free crack measurement approach was proposed based on image cross correlation algorithm. Experiment was performed to verify the validity of this method and it was found that the method is of high precision. The approach distinguished itself from traditional methods by several characteristics: it has relatively high measuring accuracy, the crack propagation can be continuously measured with this method, the amount of information that the approach provide is much more abundant than that of other methods. The method is proved to be an efficient method for crack measurement and can be applied in fatigue induced material cracking researches.