The invention discloses dibenzonaphthyridinone compounds represented by the formula (I), which is shown in the description. In the formula (I), R1a is independently chosen from -H and -CH3O, R1b is -CH3O; when R2a is -Cl, R2b and R2c are both -H; when R2b is -Cl, R2a and R2b are both -H; when R2c is independently chosen from -F, -Cl, -Br, -CH3, -CH3O, and -CF3, R2a and R2b are both -H; and R3 is (CH2)2N(CH3)2 or (CH2)3N(CH3)2. The invention further discloses a preparation method of dibenzonaphthyridinone compounds and an application of dibenzonaphthyridinone compounds in the preparation of anti-tumor drugs. The test results show that dibenzonaphthyridinone compounds have a good effect on inhibiting the activity of cells such as human stomach cancer cell (MGC-803), human lung cancer cell (NCI-H460), human liver cancer cell (HepG-2), human liver cancer cell (BEL-7404), and the like, and thus has a good application prospect in antitumor industry.