Clay minerals exert a significant influence on the petrophysical properties of sandstone reservoirs, particularly impacting pore structure and permeability. This has led to considerable research interest in their role within hydrocarbon- bearing formations. The Baikouquan Formation (T1b) conglomerate reservoir in the west area of the Mahu sag, Junggar basin, presents a compelling case study due to its complex diagenetic history and heterogeneous clay mineral distribution. This article systematically investigates the types, distribution, and genesis of clay minerals in the conglomerate reservoirs of the Baikouquan Formation. Employing petrographic analysis, scanning electron microscopy (SEM), and X- ray diffraction (XRD), we explore the influence of different clay minerals on reservoir porosity and permeability. The research results indicate that illite, kaolinite, and smectite are the main clay minerals present. Illite/smectite mixed layers play a crucial role in maintaining pore space during diagenesis, exhibiting a positive correlation with porosity. Conversely, elevated illite content is associated with a significant reduction in reservoir permeability. The presence of kaolinite helps to improve reservoir properties, especially during the later stages of fluid- filling. This is potentially due to the transformation of illite into kaolinite, further enhancing reservoir quality. In the T1b1 sub- unit, high filling intensity leads to the formation of secondary porosity through feldspar dissolution, facilitated by the presence of clay minerals. This results in significantly enhanced porosity and permeability of the reservoir. In contrast, the T1b2 sub- unit exhibits fewer clay minerals that have undergone acidic fluid alteration, resulting in poorer reservoir quality. The T1b3 sub- unit displays intermediate reservoir quality characteristics between T1b1 and T1b2. This paper reveals a comprehensive influence of clay minerals on reservoir pore structure and permeability across different diagenetic stages within the Baikouquan Formation, which provides new data support for the study of conglomerate reservoir diagenesis in the west area of the Mahu sag and provides a scientific basis for oil and gas exploration.