It is significant that remote sensing methods is used for monitoring cyanobacteria bloom in Lake Taihu, since it breaks outfrequently each year. Based on spectral characters of cyanobacteria bloom, different algorithm including single band, bandsubtraction and band ratio, were used for bloom mapping, with different instruments such as the MODIS/Terra, CBERS-2 CCD, ETMand IRS-P6. They noted that all these sensors were able to detect cyanobacteria bloom, while the algorithm of band ratio betweeninfrared and red band has a stable correlation with blooms, and it can be developed into a universal pattern. Except that, spatialcyanobacteria bloom concentrations were separated into five classes based on digital number values (DNs) in ETM and IRS-P6 Band4. This study showed that satellite observations was effectively applied to cyanobacteria bloom monitoring and early-warning forLake Taihu.