[en] 6-(4-(dimethylamine) pyridine) methyl coumarin with antitumor and radio sensitizing effect on A549 cells was synthesized through brominating and electrophonic reactions. The inhibition rate for A549 cells, the radio sensitizing effect, and the reactive oxygen species (ROS) volume were measured by MTT assay, clone formation assay (radio sensitizing effect (RSE) was calculated by the multitarget single hit model) and DCFH-DA method, respectively. The results showed that the inhibition rate for A549 cells was positive related to the drug concentration, and the survival fraction of combination group (radiation plus administration drug group) decreased significantly compared with radiation group (p < 0.05), RSE = 1.585, the ROS volume of combination group increased significantly compared with radiation group (p < 0.05) under various doses. The results indicate that 6-(4-(dimethylamine) pyridine) methyl coumarin can inhibit A549 cells and the inhibition effect increase with the drug dose, and has radio sensitizing effect on A549 cells, and can increase the ROS volume in A549 cells significantly. (authors)