Abstract: Epoxy resins, due to their excellent mechanical properties, electrical insulation, and chemical stability, are widely used in electronic packaging, composite materials, coatings, and aerospace fields. As a key component in forming a three-dimensional cross-linked network, curing agents play a decisive role in the structure and performance of the material. This paper systematically reviews the research progress of epoxy resin curing agents, focusing on three aspects: curing reaction mechanism, classification and structural design of curing agents. Firstly, it summarizes the ring-opening reaction of epoxy groups and its kinetic characteristics, clarifying the influence laws of cross-linking density and network structure on performance. Secondly, it classifies and reviews amine, anhydride, phenolic, latent, and new functionalized curing agent, and compares the structural features and application scenarios of different systems. Further, it analyzes the regulation mechanism of curing agents on the comprehensive performance of epoxy resins from the perspectives of thermal, mechanical, and dielectric properties. On this basis, it focuses on discussing the latest progress of liquid crystal and functionalized curing agents in constructing ordered cross-linked networks, enhancing intrinsic thermal conductivity, and achieving multi-functional integration. Finally, it summarizes the key challenges currently faced by epoxy curing agents, including the balance between high performance and processability, environmental friendliness, and multi-functional integration design, and looks forward to future development directions. This paper aims to provide theoretical basis and research ideas for the molecular design and application development of high-performance epoxy resin systems.