Phycocyanobilin　(PCB),　a　tetrapyrrole　chromophore　compound　of　Phycocyanin　(PC)　from　Arthrospira　platensis.　Previous　studies　have　shown　that　it　has　anti-inflammatory　and　immunomodulatory　biological　activities.　In　this　work,　we　found　that　it　can　be　used　as　a　new　anticancer　photosensitizer,　which　is　almost　non-toxic　readily　available　and　less　costly.　A　rapid　production　process　of　PCB　was　developed,　with　a　yield　of　19.2　&　PLUSMN;　1.1　mg/g.　By　using　semi-preparative　liquid　chromatography　and　silica　gel　column　chromatography,　PCB　was　refined　to　a　purity　of　99.97　&　PLUSMN;　0.02%.　Nuclear　magnetic　resonance　spectroscopy　and　mass　spectrometry　were　used　to　determine　the　PCB　structure.　The　optimized　wavelength　of　the　light　source　that　caused　PCB　to　produce　reactive　oxygen　species　(ROS)　was　660　nm.　PCB　had　an　estimated　active　oxygen　quantum　yield　of　0.1595,　14.5　times　that　of　PC　(0.0110).　Meanwhile,　PCB　produced　ROS　in　MCF-7　cells　under　light　conditions.　After　the　protein　of　PC　was　partially　removed,　the　quantum　yield　of　active　oxygen　in　PCB　is　greatly　improved,　which　was　helpful　to　enhance　its　anticancer　activity.　The　photodynamic　anticancer　activity　of　PCB　(IC50:8.26　&　PLUSMN;　1.19　&　mu;M)　was　significantly　enhanced　compared　with　PC　(IC50:255.29　&　PLUSMN;　1.72　&　mu;M).　PCB　(without　light)　had　no　significant　anticancer　activity　in　vitro,　but　it　showed　strong　anticancer　activity　in　vivo,　which　was　equivalent　to　the　activity　of　the　positive　drug　group:　Zinc-Phthalocyanine　(ZnPc)　with　light.　This　may　be　because　PCB　had　the　effect　of　eliminating　inflammation　and　improving　immunity.　PCB　significantly　enhanced　its　anticancer　activity　under　light　conditions　due　to　the　production　of　reactive　oxygen　species.　The　experimental　results　showed　that　PCB　had　dual　anticancer　effects　of　chemotherapy　and　phototherapy　in　vivo,　and　had　potential　to　become　a　new　anticancer　photosensitizer.