Effect of Buton rock asphalt（BRA）and BRA SBS polymer modifier on the performance of asphalt mixture was evaluated by laboratory test. Based on X ray diffraction test and relevant theoretical analysis, the mechanism of modification of BRA on asphalt mixture was explained. The test results show that the high temperature stability, moisture resistance and fatigue resistance of BRA asphalt mixture can reach corresponding performance of SBS modified asphalt mixture. However, the low temperature resistance ability of BRA asphalt mixture is low and can not meet the special requirement of cold region asphalt pavement surface mixture. The performance of low content SBS and BRA composite modified asphalt mixture can meet the special requirements of all temperature region pavement surface mixture. The test results by X ray diffraction indicate the mainmineral composition of BRA is calcite. The reaction between BRA and asphalt is a physically mixing process. It is due to higher viscosity and durability of asphalt in BRA that improves the performance of asphalt mixture.