Abstract: Open-pit slope ecological restoration is an important part of green mine construction. At present， there are many influencing factors， poor scheme allocation and imperfect evaluation system in the selection of open-pit slope ecological restoration scheme. The research on the optimization of open pit slope ecological restoration scheme plays an important role in promoting the construction of green mines in China. Taking the open-pit slope of Tongshankou mine as the research object， the surface fine digital model of Tongshankou mine is constructed by using the method of three-dimensional reconstruction and theoretical analysis and high-precision three-dimensional laser scanning technology. The slope zoning is studied in combination with the engineering geology of the mine slope， and seven slope zoning maps are obtained. Based on the digital identification technology of rock mass structure， the slope angle， height and rock mass joint fracture density parameters of each zone are obtained. The rock mass quality of each zone is evaluated by rock mass BQ classification method. The results show that the rock mass quality grade of zone 5 and zone 7 is grade I， Zone 1， 2， 4 and 6 is grade II， and zone 3 is grade III. On this basis， the optimization of slope ecological restoration scheme is carried out around the rock mass quality classification of slope zoning. The research shows that thick base material spraying technology is recommended for zone 5 and zone 7 slopes， three-dimensional network vegetation technology is recommended for zone 1， 2， 4 and 6 slopes， and guest soil spraying technology is recommended for zone 3 slopes. The above analysis further shows that the method of realizing the scientific zoning of slope and the optimization of ecological restoration scheme in each area by using the digital identification technology of rock mass structure has a certain reference value for improving the efficiency and quality of slope ecological restoration in open-pit mines.

Key words: ecological remediation, 3D laser scanning, rock mass quality evaluation, slope zoning, BQ classification method