Abstract: In order to solve the problem of geological disaster induced by open pits and underground goafs，dam break and regional environment damage exist in the tailings of the tailings reservoir.Regarding the metal mine of open pit to underground project as the study object，combining the sublevel open stope with subsequent filling technology， innovatively invented a device for making and sampling tailings with uneven tailings.Based on the fluid Froude criterion，combined with in-situ sampling mechanical tests on the spot， a strength calculation method that takes into account the uneven characteristics of tailings filling strength was proposed.With surveying and system engineering theory，three-dimensional information extraction of open pits and underground empty areas，and synergetic filling and drainage technology of tailings are proposed；by using fluid mechanics and finite element theory，a three-dimensional model of primary filling height and retaining wall construction parameters is optimized to form an efficient-material reuse-low-cost light retaining wall tailings filling and closing technology.The study results have been applied in the Shirengou Iron Mine and the demonstration project of the tailings filling and cleaning technology for the open pit to underground mining of 2 million tons per year of iron ore has been built，the main technical indicators are obtained as:the comprehensive utilization rate of tailings is 100%，the subsequent filling cost is 25 RMB /t，the one construction efficiency of retaining wall needs 0.016 man-hour，and the construction cost is 606 RMB /m2，which solved the bottleneck of tailings co-filling technology in open pits and underground goafs，improved the theory and technology of mine tailings disposal，achieved zero emissions from tailings， eliminated safety hazards in open pits and underground goaf， promoted the ecological civilization construction of metallurgical mines，speeded up the process of resource green mining.

Key words: Metal mine, Open pit, Underground goaf, Tailings, Synergetic filling, Clearer production