Two laboratory experiments for Radium desorption and diffusion were conducted in this work, which included 1) the Radium desorption of sediments that were under different salinities (2.8‰, 5.8‰, 8.8‰, 11.8‰ and 14.8‰) from the lake water and the potential of hydrogen from Buha River estuary. 2) Radium diffusive fluxes with time in the overlying water of lake sediments and in river sediments. We have got the desorbed activity of Radium from the suspended particles and Radium diffusion fluxes from surface sediments. The results show that the desorption activities of ²²⁴Ra are higher than those of ²²⁶Ra and ²²⁸Ra, and the desorption degrees of ²²⁴Ra, ²²⁶Ra and ²²⁸Ra have reached the maximum value when the salinity near 12‰. The desorption of ²²⁶Ra activities are greater than that of ²²⁸Ra when salinity<9‰, however, when salinity>9‰, the desorption activities of ²²⁶Ra is less than that of ²²⁸Ra, which may be associated with the local rich uranium. The diffusion fluxes of ²²⁶Ra and ²²⁸Ra of sediments from Buha River are 0.039 and 0.290 dpm/(m²·h), respectively, and they are 0.018 and 0.092 dpm/(m²·h) from Lake Qinghai, respectively. The Radium diffusion fluxes of sediments in Lake Qinghai are less than that of the river.