Abstract: The dissolution mechanism between SBS modifier and asphalt was studied with the Computer Aided Molecular Design(CAMD) method. One type of the base asphalt models was defined for 3D amorphous cell construction. Molecular Mechanics (MM) and Molecular Dynamics (MD) computations were carried out on these amorphous cell structures at customized temperatures to determine the lowest energy structures and hence the most stable configurations.The solubility parameters derived from the cohesive energy density (CED) of each amorphous cell system at different co-melting temperatures were calculated with the molecule modeling analysis module.Comparison of experimental and simulation data showed that the solubility of SBS line-shaped modifier in base asphalt was improved and reached that of star-shaped by adding a small amount of sulfur at co-melting temperature of 110℃. However,the solubility of both line-shaped and star-shaped modifiers is satisfactory at a higher temperature of 150℃ even without sulfur addition.The CAMD method could be useful in preparing SBS modified asphalt.