The Middle and Lower Jurassic in the southernYili basin is an important sandstonetype uraniumbearing sequence. This study carried out systematic analysis for lithological and geochemical features of the the Middle and Lower Jurassic clastic rocks in the southern Yili basin to understand its province features and tectonic environment. The results show that most sandstones are litharenite with low maturity, poor sorting and psephicity. Detritus consists mainly of siliceous and rhyolite fragments. It indicates the deposition of sandstone is close to the provenance. The finegrained clastic rocks has high SiO2 (ranging from 53.01% to 85.52%, Avg.71.22%) and Al2O3(ranging from 7.45% to 23.83%, Avg.13.96%), and low content of TFe2O3+MgO (ranging from 0.95% to 10.77%, Avg.3.64%) and TiO2 (ranging from 0.20% to 1.32%, Avg. 0.74%).The trace elements and rare earth elements characteristics of fine clastic rocks are similar to the upper crust. Light rare earth elements are enriched, the distribution model of heavy rare earth elements is flat. The anomalous value of Eu is negative. The trace elements and rare earth elements characteristics of fine clastic rocks suggest that the parent rocks were derived from felsic rocks in the upper crust and deposited in a tectonic setting related to continental arc. Combined with previous research data，it can be concluded that the clastic rocks in the lower and middle Jurassic in the southern margin of the Yili basin may be derived from the Carboniferous rocks in continental arc environment.