Abstract: The failure process of backfill body is also a process of energy dissipation. Factors such as curing age and delamination number directly affect the strength and energy dissipation of the backfill body. In this paper, using whole tailings as aggregate, a group of cemented backfill with mass concentration of 78%, lime−sand ratio of 1∶4, 1∶6, 1∶8 and curing age of 3D, 7 d, 14 d and 28 d were prepared for Brazilian splitting experiment. The effects of mass concentration, curing age and delamination number on the strength, energy dissipation and failure law of the backfill body were analyzed. The results showed that when the cement−sand ratio was constant, the strength of the backfill body was positively correlated with the curing age, and when the curing age was fixed, the strength and the cement−sand ratio were positively correlated, and the delamination will form the weak surface of the structure and reduced the strength of the backfill body. In the Brazilian splitting process, the energy dissipation of the backfill body increases with the increased of curing age, which was consistent with the strength change characteristics; the crack initiation point of the backfill body was mostly located at the central point of the backfill body and spread into an irregular shape to the loading diameter. The indoor test results showed that the crack initiation point of the backfill body was mostly located at the central point of the backfill body, and during failure, the main crack started to initiate and propagated from the center point with numerous microcracks until it ran through the whole backfill body. It spread into an irregular shape to the loading diameter. The crack propagation of different layered backfill bodies was more coherent, and the local dislocation of the delamination interface occurs in some of the backfill bodies, most of the fracture characteristics were the compound fracture of central fracture and eccentric fracture.