The incidence of ulcer diseases of large yellow croaker (Pseudosciaena crocea) in the cage culture was examined, and environmental factors of surrounding sea waters and weather information were surveyed in Zhoushan, during 2001-2005. Based on the data obtained, the occurrence conditions of ulcer disease and the relationship between the disease and environmental factors were investigated. The results showed that the occurrence of ulcer disease was not only related to seasons but also to the environmental factors. By means of the multivariate statistical analysis, the effects of the environmental factors on the disease were studied. The environmental factors highly related to the occurrence of ulcer disease were selected to set up models for forecasting incidence. Statistical tests showed that the forecast model was of significant efficiency for predicting the disease occurrence and the scales of diseases. The accuracy of the model reached up to 81.2% when it was used for predicting the ulcer disease of 2005 in Zhoushan. The other model was also constructed for forecasting incidence in the occurrence period in order to prevent ulcer disease timely and efficiently.