A series of novel chalcone derivatives were designed and synthesized as potential antitumor agents. Structures of target molecules were confirmed by 1H NMR, 13C NMR and HR-MS, and evaluated for their in vitro anti-proliferative activities using MTT assay. Among them, compound 12k displayed potent activity against the test tumor cell lines including multidrug resistant human cancer lines, with the IC50 values ranged from 3.75 to 8.42 μM. In addition, compound 12k was found to induce apoptosis in NCI-H460 cells via the mitochondrial pathway, including an increase of the ROS level, loss of mitochondrial membrane potential, release of cytochrome c, down-regulation of Bcl-2, up-regulation of Bax, activation of caspase-9 and caspase-3, respectively. Moreover, the cell cycle analysis indicated that 12k effectively caused cell cycle arrest at G2/M phase. The results of tubulin polymerization assay displayed that 12k could inhibit tubulin polymerization in vitro. Furthermore, molecular docking study indicated that 12k can be binding to the colchicine site of tubulin.