In order to investigate the influences of age and cement/sand ratio on the mechanical damage characteristics and fractal characteristics of damage fracture morphology of filling body, as well as the relationship between mechanical damage characteristics of filling body and fractal characteristics of fracture morphology, five types of cement/sand ratio cemented filling body samples were prepared using a certain metal ore tailings. Porosity, acoustic wave velocity tests, uniaxial compression and damage fracture morphology scanning tests were carried out on samples at four curing ages. Based on the principle of strain equivalence, the damage evolution equation of filling body was constructed to characterize the damage characteristics of filling body. The “small island method” was used to calculate the fractal dimension of fracture morphology and quantitatively characterize its fractal characteristics. The results show that the uniaxial compressive strength and elastic modulus of filling body increase exponentially with age, increase with the increase of cement/sand ratio, and show an exponential decreasing relationship with the fractal dimension of fracture morphology. The damage evolution process of filling body can be divided into three stages: initial damage, accelerated damage growth, and damage failure. The fractal dimension of fracture morphology of filling body decreases exponentially with age, and decreases with the increase of cement/sand ratio. The effect of age on fractal dimension of filling body with a larger cement/sand ratio is more significant. There is a linear negative correlation between damage value at peak stress of filling body and fractal dimension of damage fracture morphology.