To investigate the effects on cell viability and cell cycle of apigenin on BCPAP cell line, the MTT assay was used to detect the growth inhibition rates of BCPAP cells at 24 h which cultured with apigenin in different concentrations, and of BCPAP cells at 24, 48, 72 h which cultured with 12.5, 25, 50 μmol/L apigenin as well. The bright field images of cell morphology were analyzed. The effects were evaluated of different concentration of apigenin on the morphology of BCPAP cells, and the inhibition of cell growth. The cell cycle distribution was measured by flow cytometry. The different concentrations (12.5～100 μmol/L) of apigenin had cytotoxicity on BCPAP cells, which were clearly dose-and time-dependent. The IC₅₀ of 24 h is 40.65 μmol/L. There are significant effects of apigenin on the morphological changes of BCPAP cells, and the high concentration of apigenin strongly inhibited BCPAP cell growth in numbers. Cells were treated with apigenin which had significant effects on cell cycle of BCPAP cell, and induced apoptosis. Apigenin had significant cytotoxicity and inhibition of cell viability on thyroid cancer BCPAP cells. One of the mechanisms may be that it might make significant G2/M phase arrest and induced apoptosis, and a decrease of cell viability, then the cell number was declined.