Gangue grouting and backfilling mining technology is one of the key techniques to achieve solid waste disposal and rock movement control in coal mines. The pipeline conveying performance of gangue slurry determines the success or failure of backfilling engineering directly. Due to the high cost of crushing small-sized gangue, research on pipeline transportation of large-sized gangue slurry has been gradually highlighted. In this study, the gangue slurry ratio optimization test and industrial-grade pipeline transportation experiments were conducted, and the optimal ratio of gangue slurry with different large particle size grading was obtained. Additionally, the rheological parameter changes of gangue slurry in pipeline transportation were analyzed, and the changes in slurry mass concentration, slurry flow velocity, and particle size matching of pressure loss in the straight and bent pipe sections of the transportation pipeline were studied. The results show that the optimal ratio for the 0–5 mm particle size gangue slurry is the mass concentration of 65 % and a mass proportion of 0.3: 2: 1 for 2–5 mm, 0.15–2 mm, and 0–0.15 mm particle size gangue; the optimal ratio for the 0–2 mm particle size gangue slurry gangue is the mass concentration of 60 % and a mass proportion of 2:1 for 0.15–2 mm and 0–0.15 mm particle size gangue. Both the mass concentration, flow velocity, and particle size grading of the gangue slurry have a significant impact on the pressure loss during pipeline transportation. The mass concentration of the gangue slurry has the most significant impact on the pressure loss in the straight pipe section, while the flow velocity has the highest impact on the pressure loss in the bent pipe section. The research results provide a theoretical basis for the design of pipeline transportation parameters for gangue grouting and backfilling projects.