Hyperbranched polymers，with their unique three-dimensional topological structures and abundant active terminal groups，have shown significant potential in enhancing the lubricating properties of water-based drilling fluids. However，the structure-activity relationship between their molecular configurations and lubricating performance remains unclear，which hinders the development of new high-performance additives based on spatial configuration design. In this study，based on the boundary lubrication theory，the structural characteristics of multi-generation（G1—G5）PAMAM molecules and their adsorption behavior at the metal iron（Fe）interface were systematically studied by quantum chemistry and molecular dynamics methods. The structural changes of PAMAM molecules at the Fe interface during the shearing process were analyzed. The results indicated that PAMAM hyperbranched macromolecules possessed hierarchically distributed N and O active atoms，with the central N atom exhibiting the strongest electron-donating ability，followed by the terminal N atoms. As the generation increased up to G5，the three-dimensional structural stability of PAMAM molecules improved，with enhanced entanglement of molecular chains at the core and "claw-like" distribution of outer branches，which enhanced multi-point adsorption capabilities. During the adsorption of PAMAM molecules on Fe surfaces，atomic distribution extended along the interface and its normal direction，while shear promoted the aggregation of PAMAM molecules at the Fe interface，forming a transfer film that contributed to the formation of a robust lubricating layer. Finally，a lubrication enhancement model for hyperbranched polymers was proposed，which should provide theoretical support for the design of high-performance hyperbranched polymer additives.