The material composition of clastic rocks is closely related to the tectonic background and paleoclimatic conditions of the source area. The study of sedimentary geochemistry can not only trace the tectonic environment of the source area during the sedimentary period, analyze paleoclimate and environmental conditions, but also enrich and improve the scientific system of sedimentary geochemistry. Research on this aspect of the Xujiahe Formation in the Muchuan area of southwestern Sichuan Basin has not yet been carried out. Based on profile measurement and microscopic research, geochemical studies of the Xujiahe Formation in Muchuan were carried out. Research shows that: (1) The Xujiahe Formation is mainly composed of debris sandstone, with a large amount of sub-volcanic debris, a small amount of metamorphic rocks (schist, calenite) and polycrystalline quartz. The chemical analysis of major elements shows that it is rich in quartz. The material sources come from passive continental margins, active continental margins and continental island arcs; (2) The sandstone and mudstone of the Xujiahe Formation is rich in light rare earths and has obvious negative Eu anomalies. The standardized curve shapes of the average mudstone are similar. The contents of Sr, Cu and Mo are lower than those of the average mudstone. The contents of Ga, V, U, Th, Cr, Co, Sc and Rb are close to those of the average mudstone. The contents of Ba, Ni and Zn are slightly higher than or close to those of the average mudstone. The elements Zr and Hf with terrestrial properties are significantly higher than those of the average mudstone. Geochemical characteristics show that it mainly comes from feldspar volcanic rocks, sedimentary rocks, granites and andesite; (3) The source area of the Xujiahe Formation suffered from moderate chemical weathering during sedimentation and was a warm and humid sedimentary environment. Evaporation and oxidation in the basin are relatively intense, and the water body has the characteristics of brackish water, with an ancient salinity ranging from 7.10‰ to 20.60‰. During the sedimentation process, the stratification of the water body was weak to moderate, and a reducing sedimentary environment occurred locally. The origin of the Xujiahe Formation is closely related to the convergence and rifting of the Kenorland, Columbia and Rodinia paleocontinents in southern China, as well as the early Paleozoic passive continental margin basin, the Caledonian collision orogeny, the Haixi-Indosic rifting cycle and the Late Triassic Paleo-Tethys Ocean closure collision orogeny. It is a sedimentary material for the re-cycle orogenic belt. And mainly they are long-distance sources in South China, with a small amount being close-range sources in the Kangding – Yunnan Paleocontinent. The source rock type is the silicon-aluminum layer of the upper crust and they are similar; The semi-arid and oxidizing paleoclimate environment within the basin is related to the surrounding closed paleoctopographic conditions, poor air circulation and strong evaporation.