The objective of this study is to extract C-phycocyanin from Spirulina platensis using four different extraction methods and to investigate its structural， physicochemical， functional properties， and antioxidant activity. The four extraction methods include oscillatory extraction （OE）， high-speed homogenate extraction （HHE）， ultrasonic extraction （UE）， and repeated freeze-thaw extraction （RFE）. The results showed that the purity of C-phycocyanin obtained by the four extraction methods reached the standard of reagent grade. The purity of C-phycocyanin obtained by repeated freeze-thawing and high-speed homogenization methods reached 2.68 and 2.37， respectively. FTIR analysis showed that C-phycocyanin α-helix obtained by repeated freezing and thawing had the highest content， indicating that its secondary structure was the most stable. The physicochemical and functional properties of C-phycocyanin showed that its solubility， emulsification ability， foaming ability， water holding capacity， oil holding capacity， minimum gel concentration and surface hydrophobicity all showed the following characteristics： repeated freeze-thaw extraction > high-speed homogenate extraction > ultrasonic extraction > oscillating extraction （P<0.05）. As shown by SDS-PAGE profiles， C-phycocyanin obtained by all extraction methods contained two helical subunits， α and β . The results of antioxidant experiments showed that C-phycocyanin had strong antioxidant properties. The ability of C-phycocyanin to scour DPPH and ABTS free radicals obtained by the four extraction methods was shown as repeated freeze-thaw extraction， high-speed homogenate extraction， ultrasonic extraction， oscillation extraction. In conclusion， C-phycocyanin extracted by repeated freezing and thawing has the highest purity， the most stable secondary structure， the best solubility， emulsification ability， foamability， water holding capacity， oil holding capacity， minimum gel concentration and surface hydrophobicity， and strong antioxidant ability. These results provide theoretical support and research basis for expanding the application of C-phycocyanin in food， medicine and cosmetics.