A novel cementitious material (abbreviated as a cementitious powder (CP)) was developed by to achieve low-cost backfill mining. A comparative analysis of the strength test for cemented tailings backfill (CTB) was carried out to demonstrate the superiority of the CP over ordinary Portland cement (OPC). Furthermore, the deformation behavior and failure mode associated with the strength growth mechanism of the CTB assembled with CP were examined using uniaxial compression tests and micro-scanning observation. The findings indicate that CP has significant potential in replacing OPC; A higher mass concentration and longer curing age, as well as a lower tailing-to-cement ratio, have a favorable impact on the strength enhancement of the CTB; And the formation of C-S-H gel and ettringite cement the tailings particles and promote the densification of the cavity structure, thereby resulting in the high strength of CTB at the macro level. This work provides valuable insights into green mining.