The molecular composition and structural characteristics of asphalt are fundamental to its performance, particularly in pavement durability and aging resistance. This review aims to provide a comprehensive overview of current advances in the molecular-level understanding of asphalt materials. Emphasis is placed on the chemical structure, molecular transformations induced by aging and modification, and their influence on macroscopic properties. The results indicate that a comprehensive understanding of asphalt's molecular structure remains highly challenging due to its intrinsically complex and heterogeneous composition, as well as the limitations of current advanced characterization techniques in resolving such molecular-level intricacies. The mechanisms by which aging and chemical modifiers influence the molecular structure of asphalt are further analyzed, highlighting the importance of refining molecular models to more accurately represent real-world service conditions. Despite recent progress, significant challenges remain in establishing robust correlations between molecular features and engineering performance, highlighting the urgent need for molecular-level indicators capable of predicting asphalt performance. By integrating chemical insights with performance evaluation, this work offers a microscopic perspective for guiding the design of high-performance, multifunctional asphalt materials. The findings contribute to advancing the scientific foundation for asphalt research and support the development of more durable and sustainable pavement technologies.