以正硅酸乙酯作为硅源，三甲基氯硅烷作为疏水改性剂，玄武岩纤维、玄武岩纤维-高硅氧纤维复合材料、高硅氧纤维作为基体材料，通过溶胶-凝胶法和超临界干燥技术制备出3种SiO₂气凝胶复合材料，探究紫外环境下气凝胶复合材料微观结构与性能变化。结果表明紫外老化测试前，纤维作为复合材料的骨架被气凝胶紧密包裹，两者之间形成紧密结合。老化测试后玄武岩纤维/气凝胶复合材料、玄武岩纤维-高硅氧纤维/气凝胶复合材料及高硅氧纤维/气凝胶复合材料表面均出现了微坑状结构，少量纤维从气凝胶中脱离，气凝胶结构也开始变得松散，力学性能分别降低了9.8%、11.9%、9.1%，热导率则上升了8.3%、8.5%、5.4%。基于等效辐射量理论建立自然环境下紫外老化寿命的预测方程，以力学性能衰退低于10%作为失效阈值，预测其自然环境下紫外老化寿命分别为10.0、10.8、10.9 a。3种气凝胶复合材料均呈现出桥梁紫外辐射环境下长期稳定服役的潜力，有望应用于桥梁防火领域。

With tetraethoxysilane as silicon source，trimethylchlorosilane as hydrophobic modifier，basalt fiber，basalt fiber high silica fiber composite and high silica fiber as matrix materials，three kinds of SiO₂ aerogel composites were prepared by sol-gel method and supercritical drying technology，and the changes of microstructure and performance of aerogel composites under ultraviolet environment were explored.The results showed that before the ultraviolet aging test，the fiber as the framework of the composite was tightly wrapped by the aerogel，and the two formed a close combination.After the test，the basalt fiber/aerogel composites，basalt fiber high silica fiber/aerogel composites and high silica fiber/aerogel composites all had micro pit structures on their surfaces.A small number of fibers were separated from the aerogel，and the aerogel structure was also becoming loose.The mechanical properties were reduced by 9.8%，11.9%，and 9.1%，respectively，while the thermal conductivity was increased by 8.3%，8.5%，and 5.4%.Based on the theory of equivalent radiation，the prediction equation of UV aging life in natural environment was established.Taking the decline of mechanical properties below 10% as the failure threshold，the ultraviolet aging life in natural environment was predicted to be 10.0，10.8，and 10.9 a，respectively.The three aerogel composites showed the potential of long-term stable service in the ultraviolet radiation environment of bridges，and were expected to be used in the field of bridge fire prevention.