Abstract: The digitalization and information technology has added new research methods for geotechnical engineering in all aspects. The digital image technique is broadly applied in the researches of macroscopic deformation and invisible scales as well. The application in macroscopic deformation involves small scale experimental testing and large scale geo-hazard monitoring. For invisible scales, the applications are in the areas of microstructure, high-speed dynamics and acoustic imaging. The digital image technique plays a significant role in stress detection, especially in geotechnical engineering combined with photoelastic experiment.