The Changlongshan Formation of the Qingbaikou System in Xuanlong Depression is dominated. Based on an analysis of the testing result of clastic rock samples, the authors systemically discuss the enrichment mechanism of trace elements and its environmental significance and, using correlation analysis, deal with the correlativity between oxides of clastic rocks. The results show that the inflow of ancient rivers not only provided clastic sediments with sufficient terrigenous materials but also caused low salinity of sedimentary water body. These features indicate that the geochemical characteristics of the area can be used as important marks for sedimentary facies analysis.