The application of detrital geochemistry to determining tectonic setting and provenance attribute is an important means for basin analysis and also a helpful supplementary or verification method in using coarse detrital rocks to judge the background of provenance. Geochemical characteristics of 36 Tertiary mudstone samples from Kuqa depression show that the content of CaO is very high, which can somewhat dilute other major elements, trace elements and rare elements. Some reliable indicators for provenance analysis show the source rock nature of noncarbonate sediments. The REE distribution pattern is similar to that of the upper continental crust, characterized by enrichment of LREE and negative Eu anomalies. Some trace element ratios show that the source rocks are mainly felsic. According to K2O/Na2O-SiO2, La-Th - Sc and Th - Sc - Zr/10 discrimination diagrams, the tectonic setting of the provenance is similar to that of island arc. This result is different from the former research result on sandstones, suggesting that there exist specific characteristics between the orogenic inner plate and its foreland basin in sedimentary and tectonic coupling.