Abstract: OBJECTIVE To study the antineoplasmic activity of the flavonoids component extracted from Clematis huchouensis Tamura. METHODS The content of total flavonoids was determined by Ultraviolet-Visible Spectrophotometry. Polyamide column chromatography combined with ethanol elution was used to purify the flavonoids of Clematis huchouensis Tamura to obtain its extract. ELIASA was applied in measuring optical density value with the adoption of MTT colorimetric method. The meadian inhibitory concentration(IC₅₀) was determined. The effect of Clematis huchouensis Tamura flavonoids solution with the concentration varying between 100~25 600 mg·L^-1 impacting on in vitro proliferation of myeloma cells SP2/0 in mice was observed. So that its sensibility in inhibiting tumor cell growth was realized. RESULTS The flavonoids in the Clematis huchouensis Tamura extract was 82.7% by absorbance measurement of rutin standard curve in its dilution. The flavonoid content in Clematis huchouensis Tamura dry powder was 47 mg·g^-1. Flavonoid extract of 0.158 g was obtained by elution and purification of 2.843 g Clematis huchouensis Tamura extract. Inhibition rate of purified Clematis huchouensis Tamura flavonoids solution impact on proliferation of myeloma cell SP2/0 increased along with the upward tendency of total falvonoids and eventually tend to be stable. The IC₅₀ value was 408.8 mg·L^-1. CONCLUSION Flavonoids extraction from Clematis huchouensis Tamura demonstrate antineoplasmic activity with strong specificity and high sensitivity through inhibition of myeloma cells SP2/0 proliferation in mice. Its favourable dose-effect provides reference for further application of potential role in the prevention and treatment of tumor.