A significant quantity of lithic fragments is observed in the sediment of the Kumtagh Desert, which predominantly comprising coarse- grained materials such as gravel and coarse sand, as a temporary intermediate product of weathering in sedimentary parent rock, the lithic fragments, serve as the most reliable and direct indicator for determining the nature and provenance of the Desert sediments. Methods: we quantitatively analyzed the rock and mineral composition of various landforms in different parts of the Kumtagh Desert, including graben valley terrace, marginal platform, feathery dune in the northern region, as well as diluvial platform, dry riverbed, marginal dune and interdune in the southern region. For the first time in the Kumtagh Desert research history, we employed lithology microscopy identification methods using a large number of multiple samples to obtain results. Results: The findings reveal that there is a diverse range of fine gravel and coarse sand debris types present in the Kumtagh Desert. These include three major classes (igneous rock, metamorphic rock and sedimentary rock), 14 third- grade classes and 121 fifth- grade rocks. The predominant lithologies consist mainly of middle—acid effusive rocks and regional metamorphic rocks such as rhyolite, felsite, andesite, trachyte, quartzite and quartzitic rock. Whether it is a rock or a mineral is closely related to the size of the sand particles, about >90% of the gravel and 50% to 90% of the coarse sand are rock debris. The maximum lithology species is found at the grain size of 1.0mm, and the finer the sand grain, the higher the content of detrite minerals. This situation results in regional differences in lithology distribution in different regions and geomorphologic locations of the Desert due to the different grain size of the sand. Various major lithic fragments may exhibit different colour, with the dark particles are mainly composed of medium—acid extrusional rocks, while the light particles are mainly composed of quartzy rocks and felsic minerals, some of which have both dark and light colors. Notably, the lithology found in the Desert closely resembles that observed in the Altyn Tagh. The Kumtagh Desert contains not only typical dynamic metamorphic rocks found in the Altyn Tagh but also various rock types belonging to the unique ophiolite hybrid series present within Hongliugou—Lapeiquan member of the Altyn Tagh. This observation strongly suggests that coarse debris composition of the Kumtagh Desert originates from weathering processes acting upon parent rocks located within the Altyn Tagh; meanwhile differences in weathering patterns among parent rocks and the detrital output at different historical stages of mountain uplift contribute to variations between Desert lithology composition and that found within mountain parent rocks. Microcrystalline and cryptocrystalline resistant rock types are predominant components among Desert sand debris due to their resistance against weathering processes; in contrast, granitic rocks and intermediate—high grade metamorphic rocks characterized with coarse- grained (megacrystalline) structures are more prone to decomposition into individual minerals, serving as primary material sources for fine sands found within Deserts.The distribution pattern of coarse crystalline rocks and clastic single minerals exhibits a greater prevalence in the southern region compared to the northern region, while resistant rock debris is more abundant in the north and less so in the south within the Kumtagh Desert. Conclusions:The lithology of the gravel and coarse sand in different areas of the Kumtagh Desert is comparable to that of the predominant lithology in the Altun Tagh area, suggesting that the Desert debris primarily originates from alluvial and diluvium sediments in the Altun Tagh area. The southern edge of the Desert exhibits a higher proportion of coarse crystalline lithic fragments and single mineral content, while the northern part contains a greater amount of fine crystalline debris resistant to weathering. It can be inferred that initially, water power transports the Desert material along the terrain from south to north, which is then further modified by wind power near its source and in situ.