The cyanobacteria bloom in lakes and reservoirs was affected by many factors such as water temperature，nutrients and physiological-ecological feature of cyanobacteria.There are many lakes and reservoirs in Jiangxi province with varied water environments and aquatic ecosystems.In this study，we investigated Reservoir Zhelin and Lake Xinnanhu systematically and analyzed the data.Results showed that the algae were abundant in the two waters and cyanobacteria together with chlorophyta were the dominant species.The water temperature and climate in this area was fit for the growth of algae.Population of macrobenthos and zooplankton in the waters was relatively low and there are few filter feeders or predator species which can digest cyanobacteria.Community structure of fishes in the two waters was fit for control of cyanobacteria bloom，as there are many fishes living on phytoplankton.The vegetation type was simple and coverage of aquatic vascular plants was low around the water.Finally，nutrients such as N and P together with trace elements from the soil in Jixangxi region are abundant for cyanobacteria growth.These factors will be fit for the occurrence of cyanobacteria bloom and pertinence measures should be taken to prevent and control it．