Abstract: While improving resource recovery rate and economic benefits, combined surface and underground mining also triggers the complex coupling damage effect of "1+1>2" due to the space-time interaction between open-pit and underground mining, which seriously threatens the safety and ecology of the mining area. The research systematically analyzes the particularity of combined surface and underground mining in mining technology, geological influence and environmental effect, and reveals its coupling damage mechanism from three dimensions of mechanics, hydrology and land resources, including the "two-way stress interference zone" formed by the superposition of open-pit and underground mining stress, the "three-dimensional" linkage decline of groundwater level, and the aggravation of land damage caused by the synergy of surface subsidence and open-pit stripping. In view of the above problems, this study constructs an ecological collaborative restoration technology system including three core principles, three collaborative ideas and eight key technologies. The system emphasizes the development of restoration strategies based on quantitative damage assessment, and advocates the integration of "engineering-biological-recycling" multi-technology, which specifically covers the core technologies such as collaborative control of slope stress-deformation, integrated restoration and recycling of water systems, and collaborative regeneration of land functions. Finally, the current deficiencies in the cognitive depth of coupling mechanism and the long-term effectiveness of restoration technology are pointed out, and it is proposed that in the future, multi-factor coupling modeling should be deepened, low-cost and high-efficiency repair technologies should be developed, and an ecological evaluation index system should be constructed to promote the coordinated and sustainable development of resource development and ecological environment in combined surface and underground mining areas.