The nucleosides derivatives with modified in sugar or base moiety can be used as the false substrate to interfere with the metabolism of nucleic acids and to block-up the forming of protein and nucleic acids[1],so they always are paid attention to due to their good biological activities,such as anti-viral,anti-tumor and immunomodulatory activities.Thiazolidin-4-one ring is a core substructure in various synthetic pharmaceuticals which associate with diverse biological activities,and some thiazolidin derivatives[2],such as levamisole,pidotimod,and CGP52608,have been reported to be of strong immunostimulating activities.Recently,the C pseudonucleosides bearing thiazolidin-4-one were observed to have significant effects on T cell proliferation at low concentration[3].Herein,as the continuation of our studies,we would like to report the design and synthesis of a series of novel C-pseudonucleosides containing N-phenyl thiazolidin-4-one,and the evaluation of their immunostimulating activity.