Talus deposit is often seen in the hydropower projects in the southwest of China. Its mechanical properties are so complex that microstructure study is often used to reveal the essence of deformation and damage. The digital image processing technology (DIPT) is introduced to the simulation of talus deposits. Based on the study of DIPT, a Photo-To-Flac3D (PTF) auto-modeling program is developed. It is able to realize the whole process: analyzing and processing the digital image, acquiring the information and establishing the micro-model files. A new modeling method is developed for the mechanical behavior simulation of talus deposit. As an example, some talus deposit data of Gushui hydropower station is used, the micro-model of talus deposit can be established fast and correctly by the PTF from the digital photo on-site. The mechanical properties are studied by the numerical simulation of triaxial test. The results show that the talus deposit has the feature of bully in deformation while that of Unicom band under force.