Seven new chalcones, lanceolein A-G (compounds 5 and 7-12), as well as five known chalcones (1-4 and 6), were isolated from the methanolic extract of Coreopsis lanceolata flowers. The chemical structures of 5 and 7-12 were determined on the basis of spectroscopic data interpretation. All compounds inhibited the production of nitrite oxide (NO) induced by LPS in RAW264.7 macrophage cells. Also, compounds 1-6 showed moderated cytotoxicity against human colon cancer cell lines, while compounds 7-12 hardly showed the cytotoxicity. Especially, compounds 2, 5, and 6 exhibited a little higher cytotoxicity on HCT15 cells, with IC50 values of 43.7 ± 2.17 μM, 35.6 ± 0.24 μM, and 47.9 ± 1.18 μM, respectively. In the Tali assay, compounds 2 and 5 increased the numeral of apoptotic cells. These compounds also significantly promoted the expression of apoptotic proteins including PARP and caspase-3.