In this paper, the composite modified high viscosity asphalt was prepared by using the AH-70# matrix asphalt, the Middle East natural rock asphalt and the SBS modifier. The combination of rock bitumen and SBS modifier was designed by using homogeneous design method and the performance of modified asphalt was determined by penetration test, ductility test, softening point test, 60 ℃ dynamic viscosity test, Brookfield viscosity test and DSR test. The test shows that the amount of rock asphalt has a great influence on the penetration degree and the ductility, the amount of SBS modifier has a great influence on the softening point and the compound content has a positive correlation with the 60 ℃ dynamic viscosity, the Brookfield viscosity and the anti-rutting factor. Through the test analysis, SPSS software was used to establish regression model, and MATLAB software was used to calculate and analyze the optimal mix proportion of natural rock asphalt and SBS modifier: 5.4% and 6.4%, respectively.