Abstract: To search for bioactive compounds from the flower disc of Helianthus annuus L., chromatography was used to isolate and purify the chemical constituents, their structures were identified by spectral analysis, MTT method was applied to investigate their cytotoxic activities, some compounds showed moderate cytotoxic activities on SF-268, MCF-7 and HepG2 cell lines. Eleven compounds were obtained from the flower disc of H.annuus, and identified as ent-kaurane-2α16α-diol (1) and ent-kaurane-15α,16α-epoxy-17-al-19-oic acid (2), and nine known diterpenes, ent-kaurane-16β-ol (3), phyllocladan-16β-ol (4), ent-atisan-16α-ol (5), grandifloric acid (6), angeloylgrandifloric acid (7), ent-kaurane-16-en-19-oic acid (8), ent-kaurane-17-hydroxy-15-en-19-oic acid (9), ent-kaurane-16β,17-dihydroxy-19-oic acid (10), and ciliaric acid (11). Compounds 1 and 2 are new compounds, some compounds showed cytotoxic activities on SF-268, MCF-7 and HepG2 cell lines.