Abstract <p>In light of the escalating environmental pollution crisis, the pursuit of innovative, sustainable, and economically viable materials for the remediation of heavy metal-contaminated wastewater has emerged as a critical imperative in contemporary environmental science and engineering. Humic acid, as a widely distributed macromolecular organic matter, has a unique surface structure and abundant functional groups, possessing many characteristics of adsorption, complexation, and flocculation. It can bind with heavy metal ions and effectively treat heavy metal wastewater. However, there is a lack of detailed description and research on the microscopic mechanism of atomic-level interactions. As an important method for studying the electronic structure of multi-electron systems, density functional theory plays a crucial role in calculating material properties, simulating chemical reactions, and quantifying structure-activity relationships. Especially it has unparalleled advantages of revealing the microstructure and mechanism of action of materials. In this article, the current status of density functional theory, computational methods, and their application fields, combined with the structural characteristics of humic acid and its binding properties with heavy metal ions was introduced. The application research of density functional theory in the micro mechanism of humic acid and heavy metal ion binding was summarized. Meanwhile, the advantages and disadvantages of density functional theory in the micro mechanism of humic acid and heavy metal ion binding were reviewed. Finally, a focused prospect was made on the potential development directions of its future research.</p>