Abstract: Power transmission and transformation projects pose multi-dimensional threats to biodiversity through habitat destruction, electromagnetic interference, and landscape fragmentation. This study constructs a multi-scale ecological risk assessment framework for regional biodiversity by integrating indicators across genetic, species, ecosystem, and landscape levels. A weighted risk superposition model is introduced to quantify nonlinear ecological feedback mechanisms. Using the Baoji-Hanzhong 750 kV transmission project as a case study, the results reveal a clear spatial differentiation in ecological risk intensity, with higher risk levels concentrated in the northern Qinling region. In this area, the landscape fragmentation index exceeds 0.7, while the largest patch index declines to 0.28, significantly below the threshold required to sustain stable wildlife migration corridors. Forest carbon storage capacity is weakened, evidenced by a 19% reduction in litter decomposition rates and disruptions to carbon-nitrogen cycling. An edge density of 186 meters per hectare and a Shannon diversity index of 2.8 facilitte the proliferation of edge species and decline of core species. Simultaneously, a reduction in effective population size signals the crossing of genetic diversity collapse thresholds. Based on these findings, this study proposes a zoned risk management strategy based on a "prevention-mitigation-compensation" framework. This findings offer replicable technical pathways and inform integrating planning for green energy infrastructure and biodiversity conservation.