Cyclopentadienylvanadium derivatives of polyoxotungstates ［Bu4N］4［(CpV)PW11O39］ (1), ［Bu4N］4H［(CpV)SiW11O39］ (2) and ［Bu4N］4［A-β-(η5-CpV)SiW9V3O40］ (3) were synthesized, and characterized by elemental analysis, IR, 51V and 183W NMR spectroscopy. Experiment results indicate that (1) and (2) are polyoxometalate-incorporated organometallic complexes, and (3) is a polyoxometalate supported organometallic complex. Antitumoral activities were examined by MTT method. Experiment results indicate that the title complexes did exhibit to a certainty antitumor activity for HL-60 and B16.