Water-soluble artemisinin derivatives, their preparation methods, the pharmaceutical compositions containing the same derivatives and the use thereof are disclosed. The artemisinin derivatives have following formula I. It has been proved by pharmacological tests that these compounds and compositions have evident immuno-suppressive activities, and may be used in the preparation of novel immuno-suppressants for treating the diseases caused by hyperfunction of human immunity (e.g. the auto-immune diseases such as lupus erythematosus, rheumatoid arthritis, multiple sclerosis and the like), and for inhibiting the graft rejection after cell or organ transplantation.