Abstract: Using the expressed and renatured apo-α-phycoerythrocyanin to be reconstituted with phycocyanobilin, the prosthetic group in the reconstitued phycobiliproteins were analyzed with absorption spectra. When apo-α-phycoerythrocyanin was reconstituted with phycocyanobilin directly, the prosthetic group in the produced phycobiliprotein is still phycocyanobilin. However, when apo-α-phycoerythrocyanin was reconstituted with phycocyanobilin under catalysis of α-phycoerythrocyanin lyase, the prosthetic group in the produced phycobiliprotein is phycoviolobilin, which possessed the highly reversible photochemistry property.