The co-development of alluvial fans and aeolian deposits in arid regions is a common phenomenon. While wind reworking and redeposition on fan surfaces are widespread,research on their interactive sedimentation and detailed internal architecture characterization is relatively scarce. Based on modern remote sensing images and field outcrops,this study conducted detailed observations and dissection of the lithofacies,lithofacies associations,and planar distribution within the middle part of the modern Dunhuang alluvial fan. The study area primarily develops 9 lithofacies and 5 lithofacies associations,identifying two main sedimentary types: braided channel deposits and aeolian deposits. Among these,the large-scale cross-bedded sandstone lithofacies(St)and parallel-bedded sandstone lithofacies(Sp)represent typical aeolian deposits. The braided channels mainly develop 5 lithofacies associations: cross-bedded conglomerate facies-small-scale cross-bedded sandstone facies(Gt-Scs),clast-supported conglomerate facies-small-scale cross-bedded sandstone facies(Gcm-Scs),clast-supported conglomerate facies-massive sandstone facies(Gcm-Sm),lateral accretionary thin-bedded conglomerate facies-parallel-bedded sandstone facies(Gla-Sp),and clast-supported conglomerate facies-sandy conglomerate facies/pebbly sandstone facies(Gcm-Gs/Sg). Horizontally,the braided channels of the alluvial fan develop adjacent to the aeolian dunes. Vertically,aeolian sandstones and braided channel sandy conglomerates are interbedded,reflecting the alternating dominance of these two geological agents during different periods. Based on this,a depositional model controlled by cycles of dominant and subordinate agents on the lateral margins of the middle fan under an arid to semi-arid climatic background was established,characterized by “aeolian processes advance when fluvial activity retreats” and “fluvial processes advance when aeolian activity retreats”. During arid periods with prevailing monsoons,wind was the dominant geological agent,depositing thick large-scale cross-bedded and parallel-bedded sandstones. During wet periods with abundant rainfall and glacial meltwater,fluvial processes dominated the fan surface,resulting in braided channel features. This study enriches the depositional architectural models of alluvial fans and provides theoretical support for the genetic identification and hydrocarbon exploration of sandy conglomerate reservoirs within alluvial fans.