Disclosed are a derivative of nitrogen-doped phenalene-3-ketone, a preparation method therefor and application of a derivative used as a PARP inhibitor. A structural formula of the derivative of nitrogen-doped phenalene-3-ketone is as shown in the description, wherein R is hydrogen, methyl, ethyl, isopropyl, benzyl or 3-methyl-3-butenyl, and the derivative has very high activity for inhibiting PARP enzyme, thereby providing a good basis for new drug research of developing a nitrogen-doped phenalene-3-ketone compound as the PARP inhibitor so as to achieve the purpose of tumor treatment.
