Radix sp., Gyraulus sp. and Pisidium sp. are aquatic mollusc taxa. Although their fossil shells occur widely in dammed palaeo-lake sediments in the Yarlung Tsangpo valley in Tibet, their hydrochemical and hydrological implications are not fully understood. Moreover, vital effects on the trace element and stable isotope composition of the aragonite shells of these molluscs are unclear. We measured the values of δ¹³C_shell, δ¹⁸O_shell, Sr/Ca_shell and Mg/Ca_shell of the fossil shells of Radix sp., Gyraulus sp., and Pisidium sp. collected from the dammed lake sedimentary sequences at Xigazê and Lhainxiang in Tibet, with the aim of reconstructing the palaeo-hydrochemistry and palaeo-hydrology of the dammed palaeo-lake. The results show that the values of δ¹⁸O_water, Sr/Ca_water and electrical conductivity (EC) of the dammed palaeo-lake water are higher than those of the modern Yarlung Tsangpo River water. Nevertheless, the dammed palaeo-lake still exhibited a through-flow status, together with freshwater characteristics. The values of δ¹⁸O_shell and δ¹³C_shell of Gyraulus sp. and Radix sp. have a positive relationship, but their ratios of Sr/Ca_shell and Mg/Ca_shell are not correlated. Moreover, δ¹⁸O_shell in the Radix sp. shells is ~2.97 ‰ more enriched and has a stronger relationship with δ¹⁸O_water than is the case for shells of Gyraulus sp. The values of δ¹⁸O_shell and δ¹³C_shell of Pisidium sp. are similar to those of the shells of Radix sp., and we conclude that the shells of Radix sp. are the most suitable mollusc shell for recording the δ¹⁸O_water of the ambient water of water bodies in the Tibetan Plateau.