A probit model was constructed for identifying significant environmental abiotic impact factors for cyanobacterial bloom.In the model,the variable of occurrence or not of cyanobacterial bloom,which is the result of judgement on inverting pictures for cyanobacterial bloom,was used as the dependent variable,and the indices of water quality,hydrology and weather,altogether,19 indices in 3 categories,as independent variables.The model was applied to the inspection of Lake Tai in China.Through the analysis of probit model,the significant environmental impact factors for bloom outbreak in Lake Tai were systematically identified on the basis of historical data.Air temperature and nitrate concentration have positive correlation with the probability of cyanobacterial bloom outbreak,while wind speed,humidity and conductivity have negative correlation with the probability.They are the significant impact factors for bloom outbreak.The model with discrete dependent variables (binary choice economic analysis model) was introduced successfully in the research field of cyanobacterial bloom.The results are of referencial value for prediction and prevention of cyanobacterial bloom outbreak in lakes and reservoirs.