Abstract: In order to solve the problems of high cost in mine backfilling and environmental pollution brought by the stockpiling of tailings and red mud, cemented whole-tailings backfilling materials were prepared with red mud as the main component in cementitious materials. The backfilling materials have a higher compressive strength than those prepared with cement. The compressive strength of samples made of the backfilling materials cured for 28 d was up to 7 MPa, which meets the requirements of materials for mine backfilling. In addition, the new backfilling materials have good workability such as applicable flow plasticity, good water-retaining property, non-bleeding and a much lower cost than traditional cemented backfilling materials. The hydrated products and their microstructures of the hardened samples were analyzed by XRD and SEM. The results showed that most of the raw materials were transformed into ettringite and low crystallized complexity gel during the hydration reaction. As hydration went on, the structure became much denser with the interlacing of ettringite and gel, and thus good mechanical properties were obtained.