The Xiangquan thallium deposit is located in Anhui province, China, which is the first example of a thalliumonly deposit discovered in the Middle—Lower Reach of Yangtze River, east China and in the world. SmNd isotopic compositions of early and latestage fluorites in the deposit fall on two welldefined 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 oreforming solution, which formed the Tl deposit and the Cu (Fe)—Au deposits maybe belong to the same oreforming fluid system.