As the largest city on the Qinghai-Tibet Plateau, Xining faces significant environmental challenges due to intense ultraviolet (UV) radiation. Prolonged exposure to high UV levels poses health risks to pedestrians and negatively impacts overall urban livability. Assessing the shading efficiency of street trees is essential for optimizing their spatial distribution and mitigating UV exposure risks. This study integrates drone-based remote sensing and field measurements to quantitatively assess the midday summer shading effects of street trees. The study area covers 7 main roads, 21 branch roads, and 47 sample quadrats in Xining. Additionally, eleven typical street tree species were selected to analyze the influence of tree species and structural characteristics on shading performance.The results revealed several key findings: (1) The overall shading rate of street trees in Xining is relatively low, with a citywide average of only 36%. No district achieved an average shading rate exceeding 50%, with Chengbei District exhibiting the lowest rate at 29%. Furthermore, 93% of roads had shading rates below 50%, with Huangzhong Road presenting the lowest value at just 21%. These findings highlight the urgent need to improve street tree coverage to enhance pedestrian comfort and UV protection. (2) Significant differences in shading performance were observed among tree species. Populus przewalskii,Ulmus pumila cv. Tenue,Populus alba var. pyramidalis,Zelkova schneideriana,Fraxinus pennsylvanica exhibited superior shading capabilities, making them ideal candidates for increasing urban canopy cover. In contrast, Acer buergerianum demonstrated the poorest shading performance, indicating its limited effectiveness in mitigating UV radiation. These results underscore the importance of selecting tree species with high shading efficiency for urban greening projects. (3) Insufficient planting density of street trees was identified as major factor contributing to the low shading rate. The average planting rate across Xining was found to be only 48%, highlighting a substantial gap in the optimal tree coverage required for effective shading. In areas like Huangzhong Road, where shading rates are critically low, the lack of adequate tree cover exacerbates pedestrian exposure to UV radiation.Given these findings, urban renewal initiatives in Xining should prioritize increasing the planting density of high-shading tree species such as Populus przewalskii Maxim and other effective species in critical low-coverage areas. Implementing strategic tree-planting programs along major roads and pedestrian pathways will significantly enhance shading effectiveness, thereby improving urban thermal comfort and public health. Future studies should also explore the impact of tree age, canopy structure, and seasonal variations on shading performance to further refine urban greening strategies in Xining and other high-altitude cities facing similar environmental challenges.