This article investigates the characteristics and micromodification mechanisms of terminal blend (TB) composite–modified asphalts. The physical properties, micromorphologies, chemical functional groups, and thermal stabilities of the TB composite–modified asphalts are elucidated using various analytical techniques (physical property indices, fluorescence microscopy, infrared spectroscopy, and thermogravimetric analysis). The asphalts prepared from two formulations TB_5 % styrene butadiene styrene (SBS) + 1 % aromatics + 0.1 % sulfur and TB_3 % SBS + 3 % ethylene vinyl acetate (EVA) + 1 % aromatics + 0.1 % sulfur—demonstrate superior high- and low-temperature performance, along with moderate viscosity. On the microscopic level, the TB-modified asphalt containing 5 % SBS (TB_5S) forms a distinct crosslinked mesh structure surrounding a core of evenly interwoven black rubber particles. This structure largely enhances the asphalt performance. TB_5S also exhibits the highest short-term aging resistance among the samples. Under expansion and contraction vibrations of the carbon base, the TB-modified asphalt containing 5 % EVA (TB_5E) shows the highest degree of aging, whereas TB_5S shows the lowest. Although the SBS or EVA modifier alone can augment the thermal stability of the asphalt, adding both modifiers interfere with the modifier-asphalt interaction. This phenomenon explains the lowered thermal stability of the TB-modified asphalt containing 3 % SBS and 3 % EVA (TB_3S3E).