Temporal variation of dissolved 87Sr/86Sr in the Yangtze River is poorly understood compared to other Tibetan rivers. In this study, dissolved Sr and 87Sr/86Sr were measured from a temporal series of water samples collected biweekly at Datong Hydrological Station over a period of one year. Our results show that Sr concentration in the Yangtze River ranges from 1.74 to 2.92 μmol/L with 87Sr/86Sr of 0.710125 to 0.710965. The Sr concentration and 87Sr/86Sr shows a distinct seasonal variation, with a general increase in 87Sr/86Sr ratios from summer to winter and some fluctuations during July and December, then followed by a gradually decrease till the next rainy season. The seasonal variation results from the variation of contributions from different sub-basin due to the spatially and seasonally variable rainfall across the basin. During the flood season, more contribution from upper reach (low 87Sr/86Sr values) due to the strong rainfall decreases the 87Sr/86Sr ratio at lower reach. While the severe drought which happened in the middle-lower reaches (high 87Sr/86Sr values) from January to May explains the decrease in the later part of the data by the decrease of the contribution from middle-lower reaches. The discharge weighted annual 87Sr/86Sr and annual Sr flux of the Yangtze River based on the time series data are 0.710628 and 1.9×109 mol/a, respectively. It was also indicated that dissolved 87Sr/86Sr in the Yangtze River is well correlated to the extreme climate events and might contribute to our explanation for reconstructing past climatic changes by using 87Sr/86Sr ratios of the sedimentary record in the delta .