INTRODUCTION IN order to have an acceptable bitumen to making hot mix asphalt, it must have some specified characteristics. To have suitable bitumen that can be used to making HMA there are many methods to modify and improve the properties of it. One of these methods is using polymer modifiers such as SBS, PPA, SBR and etc. Each modifier changes some of properties of the base bitumen. One of the polymer modifiers is Styrene-Butadiene-Rubber (SBR). There are some studies about the effect of this modifier on bitumen. Khadivar and Kavussi worked on rheological characteristics of SBR and NR polymer modified bitumen emulsions at average pavement temperatures. In this research the effects of SBR and NR polymers on characteristics of various bitumen emulsion binders were analyzed. Binders were tested applying fundamental and rheological bitumen tests. Temperature sweep and Multiple Stress Creep and Recovery testing were performed to characterize the rheological properties in linear and non-linear modes. In linear region, the presence of polymers improved stiffness and elastic properties of residual binders of the bitumen emulsions appreciably. Comparing the behavior of the two polymers in non-linear region resulted that SBR was more sensitive to applied stresses. Additionally, NR latex increased stiffness values of the emulsion residues substantially; while; their elastic properties were remained unchanged. Zhang and Hu (2013) evaluate the properties of modified bitumen by SBR and SBS combine. Zhang and et al evaluate the improved properties of SBR/weathered coal modified bitumen containing carbon black. Zhang and Yu worked on high performance SBR compound modified asphalt. This research shows that high-performance SBR compound modified asphalt can be made with the addition of polyphosphoric acid (PPA), styrene–butadiene rubber (SBR) and sulfur. The effects of PPA, SBR, and sulfur on the physical properties, the dynamic rheological properties, the high-temperature storage stabilities, the morphologies and the internal structures of asphalts were studied, respectively. The high-temperature storage stability of SBR-modified asphalt can be improved significantly with the addition of PPA and sulfur by the gelation effect and the dynamical vulcanization. The addition of SBR to the pure PPA modified asphalt improved the lowtemperature physical properties with unfavorable effects on the resistance to rutting. The addition of sulfur to the PPA/SBR-modified asphalt improved the rheological properties and the adhesion of modified binders to stone matrix. The optimal proportion of PPA, SBR, and sulfur can improve the properties of asphalt roundly. Yildirim worked on polymer modified asphalt binders. According to this paper polymer modification of asphalt binders has increasingly become the norm in designing optimally performing pavements, particularly in the United States, Canada, Europe and Australia. Specific polymers that have been used include rubber, SBR, SBS and Elvaloy®. Specifications have been designed and pre-existing ones modified to capture the rheological properties of polymer modified binders. The elastic recovery test is good at determining the presence of polymers in an asphalt binder, but is less successful at predicting field performance of the pavement. In this paper the effect of SBR on complex modulus and phase angle are evaluated. CONCLUSION According to this research by using SBR as bitumen modifier the complex modulus and phase angle have better values than base bitumen. Also will have better results in modified bitumen than unmodified one. Considering results 5 percent of SBR as bitumen modifier will increase the performance of bitumen more than 3 and 4 percent of this polymer modifier. In higher temperature than 40°C the bitumen modified with 5 percent of SBR has better results for all parameters include Complex modulus. But for temperature lower 40°C in all three cases the changes were same. As the results show, modified bitumen with SBR will have better performance against some distresses such as rutting and fatigue cracking and also the modified bitumen has greater complex modulus than base bitumen.