Abstract: Under the dual intense pressure of global climate change and human activities, alpine steppe ecosystems have experienced increasingly severe degradation. Accordingly, ecological restoration engineering has emerged as an important approach to maintaining the ecological security of these regions. Conventional methods for ecological restoration engineering suffer from limitations in three-dimensional spatial representation and multi-dimensional ecological response analysis. In this context, this study developed a novel monitoring and evaluation method for ecological restoration engineering that integrates unmanned aerial vehicle (UAV)-based oblique photogrammetry, uncrewed surface vessel (USV) multibeam bathymetry, and multi-source remote sensing imagery. The proposed method enables precise acquisition of surface-subsurface integrated, two- and three-dimensional spatiotemporal remote sensing data. A representative water conservation and ecological restoration project in Hongyuan County, Sichuan Province was investigated as an application model. Specifically, the proposed method was applied to multi- temporal, multi-scale, and stereoscopic monitoring of ecological restoration in the project. Accordingly, a comprehensive evaluation indicator system for alpine steppes was established, covering performance target completion, ecological restoration engineering quality, and ecological restoration effectiveness in alpine steppes. Using this system, the actual effectiveness of the project was quantitatively assessed. The results indicate that the newly increased water surface area in the project exceeded the design target by 44.9%. The indicators for ecological service functions, including soil and water conservation, along with windbreak and dune fixation, were significantly improved, yielding a comprehensive evaluation score of 79.88. Overall, the proposed method improves monitoring dimensions and efficiency while also significantly enhancing the visualization of ecological restoration effectiveness. Therefore, this method provides a replicable and generalizable technical approach for ecological restoration evaluation of alpine steppes.