The photocleavage abilities of a novel family of compounds, 8-oxo-8 H -acenaphtho[1,2-b] pyrrole-9-carbonitrile and its derivatives(compounds 1-5) were evaluated with M13 mp18 single strand circular DNA. Only compound 1 with a diethylamine group could bind to DNA via electrostatic attraction and intercalation. At a concentration of 50 μmol/L, it could generate singlet oxygen to cleave circular DNA into linear DNA under the irradiation of long wavelength light(λ>400 nm). The antitumor ability of compound 1 was also evaluated in vitro, and its IC50 on HeLa cells was as low as 6.8 μmol/L.