The brittleness of the cemented tailings backfill (CTB) can easily cause collapse, which seriously threatens the safety of underground mining workers and equipment. Studies have shown that fibers can improve the ductility of the CTB. However, there are still few existing studies on the mechanical behavior of com-bined fibers. In this study, glass (G) fiber and polypropylene (PP) fiber were adopted to prepare fiber-reinforced CTB (FRCTB) specimens. The three-point bending and scanning electron microscopy (SEM) tests were adopted to investigate the mechanical properties of CTB and FRCTB. The main conclusions were shown that: the flexural strength (FS) values of FRCTB specimens first decreased and then increased with the glass fiber content decreased. However, the residual FS values of all FRCTB were larger than those none fiber-reinforced CTB. The average flexural modulus of all the FRCTB first decreased and then increased with the content of glass fiber decreased. The average toughness index (ATI) values of all FRCTB specimens were larger than those none fiber-reinforced CTB. Indicating that the addition of fibers can improve the bending performance of the CTB specimens. The failure patterns of the CTB were mainly the tensile failure along the loading direction. The main hydrate products were still AFt and C-S-H gels. The combined fibers had an impeding effect on crack propagation. The results of this study can provide references for elaboration combined fiber-reinforced mechanism of FRCTB and serve the industrial application. (c) 2021 Elsevier Ltd. All rights reserved.