On the basis of the component analysis of reclaimed rubber and reclaimed plastic, the reclaimed rubber plastic alloying agents(RPAAs) with different mixing ratios(by mass) of reclaimed rubber and reclaimed plastic were prepared and the blend mechanism of reclaimed rubber and reclaimed plastic was studied. Then reclaimed rubber plastic modified asphalt(RPMA) was prepared with the optimized RPAA, and the modification mechanism of RPAA on matrix asphalt was analyzed. Technical performance and storage stability of RPMA were also evaluated. The research shows that reclaimed rubber and reclaimed plastic exhibit good compatibility at the mixing ratio of 7∶3. The physical action is the main form during blend process of reclaimed rubber and reclaimed plastic and modification process of RPAA on matrix asphalt. RPAA shows good compatibility with matrix asphalt. RPMA shows good technical performance and storage stability. RPAA can greatly improve the road performance of matrix asphalt, and shows application potential in road engineering.