Abstract: Using steel slag and tailings as the main filling material，this paper determined the optimized ingredient of the backfilling materials by analyzing the strength characteristics and mortar fluidity. X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) were used to observe microstructure and hydration products. The experiments result indicated that mortar fluidity can of artesian cemented filling and the 28 d compressive strength is 3.73 MPa which can satisfy the requirement of compressive strength for mine filling when the content of steel slag，desulphogypsum，and slag is 63%,12%，and 25%.

Key words: Steel slag, Cemented backfilling, Whole-tailings