Abstract: The variation of uranium isotopes along the main channel of the Yellow River and the fluxes of dissolved uranium from the river to the sea have been studied.Dissolved uranium concentration exhibited an increasing trend from the upper reaches to the lower reaches along the main channel of theYellow River.Except the high value near the source, the ²³⁴U/²³⁸U activity ratios kept in a relatively stable level in the Yellow River (1.3~1.7).Dissolved uranium concentrations at station Lijin ranged from 2.72±0.18 μg/L to 7.57±0.66 μg/L, averaged 5.49±0.28 μg/L, with a seasonal variation of lower concentrations in summer and fall compared with winter and spring.Monthly fluxes of water, sediment and dissolved uranium changed notably, and concentrated in the periods of the Water-Sediment Regulation Scheme and rainfall flood.Monthly flux of dissolved uranium was mainly controlled by water discharge at station Lijin.The fluxes of dissolved uranium at station Lijin were 1.04×10⁵ kg/a, 1.31×10⁵ kg/a and 6.41×10⁴ kg/a in 2010, 2013 and 2014, respectively, which accounted for 1% of the dissolved uranium flux of the whole world rivers.