Detection of cyanbacteria blooms in Taihu using vegetation index data from MODIS was carried out since cyanbacteriablooms broke out in May 2007. The results showed that MODIS was able to detect cyanobacteria bloom effectively. Algorithm ofband ratio between infrared and red band and values of NDVI or EVI can be used to analyze the distribution of algae. However, theformer two were difficult to distinguish high-turbid water from algae or identify areas with low density of cyanbacteria, whichresulted in the magnified or reduced areas of algae, while the latter one could constrain background noise properly mainly from waterand suspended matter. Therefore, based on the digital number values (DNs) of EVI band, an approximately actual distribution ofalgae was induced. The study showed that satellite observations could be effectively applied to cyanobacteria bloom real-timemonitoring system for Lake Taihu.