Tunnel fire resistant asphalt can be prepared by mixing SBS modified asphalt and BFR-Ti/ZB. The combustion performances of the SBS modified asphalt/BFR-Ti/ZB and the synergism mechanism of the BFR-Ti and ZB are studied systematically through different methods, such as oxygen index (LOI) method, density of smoke, cone calorimetry, thermogravimetric analysis, etc. The result indicates that compared with SBS modifiedasphalt/BFR-Ti, BFR-Ti/ZB has synergistic effect which can make smoke density, heat release rate(HRR), mass loss rate(MLR) and effective heat of combustion(EHC) of SBS modified asphalt/BFR-Ti/ZB systems significantly decrease while the oxygen index of the SBS modified asphalt/BFR-Ti/ZB and the practice carbon content increase. SBS modified asphalt/BFR-Ti system has significant endothermic-antiflaming mechanism and condensed phase flame-retardance character. SBS modified-asphalt / BFR-Ti/ZB is based on the condensed phase flame-retardance mechanism while with synergistic flame-retardance and endothermic-antiflaming mechanism.