Fresh blue algal from Chao Lake was used in this study. The crude extracts of phycocyanin were obtained with freeze-thaw method. The purification of phycocyanin was performed by combining two-step salt precipitation and two-step column chromatography. The reagent grade phycocyanin was achieved. Phycocyanin and impurity solution were obtained respectively in various stages subjected to the UV-Vis absorption spectrum scanning. With the development of the four-step purification process, the absorption peak of phycocyanin solution was redshifted from 260 to 280 nm in the wavelength range from 250 to 300 nm, and the maximum absorption peak of phycocyanin was redshifted from 617 to 620 nm in the wavelength range from 500nm to 700 nm. In the wavelength range from 250 to 700 nm, it showed that the impurity solution mainly contained impurity proteins and part of the phycocyanin in the first salting out, and mainly contained nucleic acids and vitamins substance in the second salting out. The first outflow components mainly contained phycoerythrin separated by the first column chromatography. The last outflow components mainly contained allophycocyanin separated by the second column chromatography. After the four-step purification process, the final purity of phycocyanin (A620/A280) is greater than 4,which met the standard of reagent grade．Thus it can be seen that two-step salt precipitation had a main function which was to remove impurity proteins, nucleic acids and vitamins substance, and two-step column chromatography main function was to remove phycoerythrin and allophycocyanin which were similar to phycocyanin.