As a result of silicate overgrowth, clay coatings influence the evolution of reservoir quality during diagenesis. Most studies indicate coatings can resist compaction and inhibit cementation, thus preserving primary porosity and serving as one of the primary controlling factors for improving reservoir quality. However, some research suggests clay coatings have insufficient hardness to resist compaction and could potentially block pore throats and prevent fluid flow within the sandstone, negatively affects reservoir quality. Therefore, to address whether coatings are positive to reservoir evolution, this study employs polarized light microscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and porosity-permeability testing to investigate the characteristics of clay coatings within the fluvial facies sandstone of the Xiashaximiao Formation. The microscopy reveals abundant clay coatings were found, mainly in lithic-arenite with 30%–45% feldspar and rock fragments. The underlying Lianggaoshan Formation locally exhibits interbedded siltstones with volcanic rock fragments, providing material sources for the clay coatings formation. SEM and EDX analyses indicate two predominant forms of clay coatings: single-layer (primarily chlorite) and double-layer (inner smectite/illite, outer ferroan chlorite). Single-layer overgrowths primarily consist of thin layers of chlorite (5–15 μm), whereas double-layer overgrowths consist of a thin inner zone (1–5 μm) covering the grain surface and a thicker outer zone (10–20 μm) covering the inner zone, demonstrating characteristics indicative of multi-stage growth. Porosity-permeability testing results the sandstone samples have <10% porosity, which are typically tight sandstones, but those with clay coatings have higher porosity. Nevertheless, sandstones with double-layer overgrowths exhibit lower permeability relative to those with single-layer overgrowths or without overgrowths. Therefore, based on the integration of morphological and physical properties of silicate overgrowths, it is proposed the efficiency of clay coatings in resisting compaction, inhibiting cementation, and preserving primary porosity increases with the number of growth stages, layers, and thickness, which in turn depends on the abundance of source materials. Single-layer coatings facilitate fluid migration, whereas thicker double-layer overgrowths are prone to occluding narrow pore throats, thereby restricting fluid mobility. Consequently, this study establishes a model for the multi-stage evolution of clay coatings overgrowths, elucidating the varying fluid migration behaviors across different stages and providing a more detailed investigation of the implication of clay coatings on reservoir quality, thus offering new theoretical insights into diagenesis and the evolution of tight sandstone reservoirs.