China has implemented a series of major ecological projects on a large scale. Evaluating the effectiveness of these projects serves as a pivotal tool to ascertain whether the actual outcomes align with the envisaged objectives. Moreover, it aids in tailoring and refining management measures with specificity, propelling the realization of ecological conservation and restoration objectives. In this study, we conducted a comprehensive evaluation of the ecological efficacy of ten major ecological projects in China. Through a thorough review of relevant literature and rigorous analysis, we assessed these projects in terms of their impacts on ecosystem quality, function and biodiversity. We also dissected the various factors influencing their effectiveness and summarized the sources of uncertainty in these assessments. The findings of this study provide compelling evidence of the substantial ecological benefits resulting from these projects, encompassing improvements in land greening, carbon fixation, soil conservation, water conservation and biodiversity protection. Specifically, they have contributed to a remarkable increase in vegetation cover in the project areas (0.19%-26%) and exhibited overall positive trends in biomass (-13%-187%), carbon sequestration (-7.41%-200%), soil conservation (-26.91%-151.52%), water conservation (-64.66%-80.24%), species richness (-16%-441%), evenness index (-6%-28%), and diversity index (-5%-315%), as indicated by median multi-year rate of greater than zero. Despite the considerable successes observed in various regions, these ecological initiatives have encountered a myriad of challenges that have complicated their outcomes. Some regions have experienced issues such as declining biomass, reduced soil retention capacity, diminished hydrological benefits and biodiversity loss. The relative contribution ratios of ecological engineering versus climate change ranged from 0.06 to 3.60, exhibiting significant spatial disparities between human interventions and natural climatic processes, as well as interactive coupling or synergistic effects. The mechanisms for decomposing the coupling effects of multiple factors and the intricate ways in which these factors combine and influence ecosystems at a local level require in-depth research. The assessment process itself is plagued by considerable uncertainty due to variations in assessment objects, data sources, scales, benchmarks, methodologies and the decomposition of driving factors. Future research in this domain should prioritize the selection of appropriate evaluation benchmarks and scales, as well as the fusion and assimilation of diverse source data. Additionally, enhancing the assessment technology system for ecological engineering is crucial. It should also consider regional geographical zoning differences, appropriateness and effectiveness of engineering measures, trade-offs in ecosystem services, and spatial variations in the contributions of driving factors. Ultimately, these insights will fine-tune and optimize engineering restoration measures.