Abstract: In order to research the law of blue algae bloom in Lake Chaohu, this paper used the Landsat satellite image as a data source and extracted algal blooms by AFAI index to analyze the temporal and spatial variation of the blue algae bloom in Lake Chaohu and the main driving force of blue algal bloom outbreaks in Lake Chaohu was discussed. The results showed that the frequency and duration of outbreaks of blue algal blooms in Lake Chaohu from 1983 to 2017 increased; the earliest time of the outbreaks in the calendar years gradually advanced; the area covered by algal blooms showed an overall increase trend. Lake Chaohu algae is mainly distributed in the northwest entrance to the lake, and the northwest is the core area of blue algal blooms in Lake Chaohu. From the analysis of its driving forces, the atmospheric pressure, air temperature and wind speed were important factors affecting the outbreak of Lake Chaohu. In addition, the Lake Chaohu population growth, rapid GDP growth, increased fertilization and increased domestic sewage discharge were important human factors that caused the blue algae bloom phenomenon in Lake Chaohu to become increasingly serious.