This research was performed to improve the quality of Bituminous mixes, and improve the thermal resistance of the surface bituminous layer, the bitumen has a various changes, that which begins from the production of the bituminous mixture in high temperatures, these changes continues to the phase of it's use. For this purpose, SBS(Styrene Butadien Styrene) was selected to be an improving material to bitumen according to the rate: 3.5% for SBS.in my research I work on modifying the local bitumen by adding the SBS so that the modified bitumen can be used to design bituminous mixes within the limits of bituminous mixes designed specifications, and improve it's thermal resistance. some experiments were held to determine the qualities of the modified and unmodified bitumen,befor and after Lose Of Heating, the results were within the specifications 'limits. According to Marshal's method, samples of Bituminous mixes were prepared for all Bituminous sorts used in our research. These samples were put under required tests, and samples were prepared according to an ideal rate of Bitumen. the result was the Bitumen modified by adding SBS improve the quality of Bitumen to thermal resistance.