Taking cyanobacterica blooms water samples collected from 12 different sites in Meiliang Bay of Lake Taihu in August 20,2011 as a research object,the phycocyanin extraction method including freeze thawing cycle,ultrasonic wave extracting,cellmelting and acetone were compared based on absorption spectrum and phycocyanin concentration.Results showed that the absorption spectrum of phycocyanin extracted by these methods have significant peak at 620 nm.The peak height is quite different among these methods: the highest peak is observed in freeze thawing cycle while the lowest in ultrasonic wave extracting,indicating that the four methods can extract phycocyanin from water samples,and freeze thawing cycle method is superior to others;Some phycocyanin specturm obtained by freeze thawing cycle,ultrasonic wave extracting and cell-melting appeared the second peak near 670 nm,and differentiated with the specturm of phycocyanin standard sample;The variation coefficient of phycocyanin concentration in the freeze thawing cycle method and ultrasonic wave method are less than 0.6,showing that their result is more precise and stable;The phycocyanin concentration showed that extraction efficiency of freeze thawing cycle method is better than the others,and so is recommended as a common method for phycocyanin extraction from cyanobacterica blooms water samples in Lake Taihu.