A kind of smokeless waste rubber powder modified asphalt was prepared.The influence of smoke suppressant dosage on smoke emission and performance of modified asphalt was investigated. The mechanism of smoke suppressant was analyzed. The results show that smoke emission of 1.0% smoke suppressant dosage is reduced from 700 mg/kg to 60 mg/kg. The penetration， softening point and ductility changed little， and the aging performance is improved. Smoke suppressants inhibites the degradation of waste rubber powder. The initial decomposition temperature of the modified asphalt increases， the residual mass increases， and the thermal stability is improved.