The invention discloses a derivative based on a PARP inhibitor Niraparib. The derivative has a structure shown in a formula I as shown in the description, wherein R1 is selected from alkyl, alkoxy, cycloalkyl, aryl alkyl, cycloalkyl alkyl, heterocyclyl, aromatic heterocyclyl, haloalkoxy, haloalkyl or hydroxyalkyl. The invention also provides a preparation method of the derivative and a use of thederivative in preparation of an antitumor drug. The compound disclosed in the invention is an inhibitor for poly (ADP-ribose) polymerase, and thus can be used for treating tumor diseases such as breast cancer, ovarian cancer, prostate cancer, pancreatic cancer and the like, and further can be used as a chemical/radiosensitizer for cancer treatment.