Abstract: The work aims to study the difference between recycled coarse aggregate concrete and normal concrete in failure mode and internal crack propagation. The recycled coarse aggregate concretes with different recycled coarse aggregate (RCA) replacement rates were used as the research object. Using the micro-focus industrial CT (Phoenix v | tome | x s240), 2D scanning images of recycled coarse aggregate concrete under 90% predicted failure load were obtained. With Photoshop CS6 image processing software, the failure crack in material was extracted. After that, based on the fractal geometry theory, the fractal dimension and multi-fractal spectrum were used to characterize the fractal propagation law of crack. Finally, the relationship between fractal dimension, multi-fractal spectrum characteristic parameters and RCA replacement rate and compressive strength was established. The results show that the meso-failure mode of recycled coarse aggregate concrete is different from that of normal concrete. The failure form of recycled coarse aggregate concrete depends on the interfacial transition zone (ITZ) between the coarse aggregate and the cement paste and the properties of RCA itself. When the crack develops to the natural coarse aggregate (NCA) or the RCA with higher strength, it will continue to develop around the surface of the aggregate, and it will penetrate through the aggregate when it is developed to the RCA with lower strength; The fractal dimension can quantitatively describe the overall propagation of meso-crack inside the concrete materials, that is, the richer the crack, the larger the fractal dimension; Multi-fractal spectrum can reflect the characteristics of meso-crack at different levels from local to global; The fractal dimension and multi-fractal spectrum characteristic parameters of crack have a linear negative correlation with the RCA replacement rate, and have a linear positive correlation with the compressive strength; This study can lay a theoretical and experimental basis for the wide application of recycled concrete in large-scale structural engineering.