In view of the high cost of cement cementing material filling in Jinchuan mine, the low cost cementitious material was developed with ground granulated blast furnace slag (GGBFS) as the main raw material, and the ratio of the slurry was optimized to meet the requirements of the mine in order to reduce the filling cost. Firstly, physicochemical analysis and particle size gradation analysis of the experimental materials were carried out; Secondly, orthogonal test and range analysis were used to optimize the proportion of new cementitious materials. The optimal proportion was determined as follows: the mass fraction of clinker, desulfurization gypsum（DG） and GGBFS were 8%，14%， and 78%，respectively. XRD and SEM were used to explore the hydration products and their microstructures of the new cementitious materials，and to reveal their hydration mechanism. Finally，on this basis, the filling slurry proportioning test was carried out, and the slurry proportioning was optimized based on multi-attribute decision method with 7 d strength，28d strength，slump，bleeding rate（BR） and filling cost as the evaluation indexes. The results show that that when the composite cementitious material is used，the optimum mass proportion ratio of waste rock rod grinding sand (waste sand ratio) is 7 ∶ 3，the ratio of cement and aggregate is 1 ∶ 4，and the slurry mass fraction is 80%. Moreover，the verification test is carried out with above proportion. The corresponding 7 d strength, 28 d strength，slump and bleeding rate are 4.36 MPa，6.62 MPa，26.8 cm and 11.1%，respectively，which meet the requirements of the mine. And the filling cost is 139 yuan/m3，which is 29.8% lower than the original filling cost of 198 yuan/m3.