Abstract:The Xiangquan thallium deposit is located in Anhui province, China, which is the first example of a thalliumonly deposit discovered in the Middle—Lower Reach of Yangtze River, east China and in the world. SmNd isotopic compositions of early and latestage fluorites in the deposit fall on two welldefined lines in the isochron plot with isochrons corresponding to 131.7±2.7 and 79±11Ma. The isochron ages suggest that epithermal thallium mineralization took place in the Early Cretaceous period (Yanshanian period), which experienced an alteration of hot spring in Late Cretaceous period. The epithermal thallium mineralization maybe has close relationship with the copper (iron)—gold hydrothermal mineralization.The oreforming solution, which formed the Tl deposit and the Cu (Fe)—Au deposits maybe belong to the same oreforming fluid system.