Tibet intense ultraviolet radiation,large DIF and other climatic conditions put higher re-quirement on aging resistance and low crack resistance of asphalt mixture.To improve the durability of as-phalt mixture in Tibet,this article is subject to Tibet highway Lalin and proposed using polyphosphate and rubber powder composite modified asphalt,using rutting test study on the effects of the rubber powder and poly phosphoric acid(PPA)content on of the high temperature stability of composite modified asphalt mix-ture,and based on laboratory simulation aging tests,to study the affect of cracking resistance of composite modified asphalt mixture before and after heat aging and UV aging with different PPA and rubber powder content,Accelerated loading test out the preferred composite modified asphalt complex programs were screened,and with SBS modified bitumen were compared.recommend the best solution for 20 percent compound rubber powder +1.25% PPA.%西藏地区紫外线辐射强烈、昼夜温差大等气候条件对沥青混合料的抗老化性能和低抗裂性提出了更高要求。为改善西藏地区沥青混合料的耐久性，以西藏拉林高速公路为背景提出采用多聚磷酸与橡胶粉进行复配，在优选出4种复配方案的基础上，采用车辙试验研究了橡胶粉和多聚磷酸（PPA）掺量对复合改性沥青混合料高温稳定性的影响，并基于室内模拟老化试验，采用低温弯曲试验研究了紫外线老化与热老化前后 PPA 与橡胶粉掺量沥青混合料低温抗裂性能的影响，采用加速加载试验对优选出来的复合改性沥青复配方案进行了筛选，并将其与 SBS 改性沥青进行了对比。推荐最佳的复配方案为20％橡胶粉＋1.25％PPA。
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