<p>In order to clarify the structural framework of faults, folds, and stress fields in the Mahaidong area of the Qaidam Basin and their controlling effects on hydrocarbon reservoir formation, this study, based on the regional tectonic background and stratigraphic framework, carried out tectonic unit division, systematically characterized fault properties and fold evolution, and, in combination with multi-stage stress-field variations, established a coupled analytical framework between structural elements and petroleum accumulation elements. The results show that the tectonic style of the study area is characterized by the coexistence of fault segmentation and fold deformation. Normal faults, reverse faults, and strike-slip faults are all developed. Faults can act as both vertical and lateral migration pathways, but may also lead to trap destruction and hydrocarbon loss when reactivated in the late stage or when their sealing capacity is insufficient. Under a compressional regime, folds experienced a staged evolution of initial deformation, intense deformation, and late-stage adjustment. Variations in the orientation and intensity of multi-phase stress fields resulted in different combinations of structural lineaments and controlled the spatial differentiation of hydrocarbon accumulation. Meanwhile, tectonic subsidence coupled with folding jointly influenced the burial evolution of source rocks and the structural modification of reservoir fractures. The continuity and integrity of cap rocks are significantly constrained by fault cutting and strain concentration, thereby determining the accumulation and preservation pattern of hydrocarbons. This study is of great significance for sweet-spot evaluation and target optimization in the Mahaidong area.</p>