A fast-melting epoxy resin styrene-butadiene-styrene composite modifier (ER-SBS-T) was utilized for the rapid modification of an asphalt binder. The effect of this novel fast-melting modifier on high-temperature performance is not supported by any pertinent investigations. First, the penetration, softening points, and 60 °C kinematic viscosity of the asphalt samples were tested. In addition, these asphalt samples were subjected to multiple stress creep recovery (MSCR) tests to assess the ability to recover from creep and to test the high-temperature performance of the asphalt binder. The study then compared different models based on the zero-shear viscosity (ZSV) test. The research shows that the use of ER-SBS-T composite modifiers significantly improves the high-temperature performance of asphalt binder. The high-temperature performance of fast-melting SBS-T-modified asphalt binder is comparable to that of SBS-modified asphalt binder. The high-temperature performance of the asphalt binder can still be significantly improved when the amount of ER-SBS-T composite modifier exceeds 6%. For the high-temperature performance grading of the ER-SBS-T composite-modified asphalt binder, a reference temperature of 70 °C can be established. The results also demonstrate that the Cross rheological model is more suitable for determining the zero-shear viscosity of the ER-SBS-T composite-modified asphalt binder.