In the process of digital image correlation measurement calculation, the speckle subimages are directly used for crosscorrelation calculation, and the quality of speckle subimages has important effect on the measurement accuracy. Therefore, how to effectively assess the quality of speckle subimage is a point issue in the study of digital image correlation method. The concept of entropy, which was used to measure the amount of information in information theory, was introduced into the assessment of speckle subimage, and then a new method for quality assessment of speckle subimage based on image entropy was proposed. In order to verify the validity of the assessment parameter, the displacement measurement experiments were carried out on three different types of speckle subimage obtained by different methods. The experimental results show that the accuracy of displacement measurement is closely related to the speckle subimage entropy, the bigger the entropy of speckle subimage is, the higher the accuracy of displacement measurement is. The experimental results verify that the image entropy can be used to assess the quality of speckle subimage effectively.