Abstract: Based on the data of monitoring on potato late blight,the relationship between the occurrence and development of potato late blight and meteorological conditions was analyzed. The main climate factors affected the potato late blight occurrences were determined. The result showed that the relative humidity,precipitation and air temperature were positively related to the occurrences of the potato late blight. It was favorable to the development of potato late blight as the temperature,relative humidity and precipitation increased,while it was not favorable to the development of potato late blight as the sunshine duration,average wind velocity increased. The meteorological conditions were the dominant factors affected the occurrences of the potato late blight. The model for forecasting the grade of meteorological conditions of the potato late blight was established,based on the data of the potato late blight occurrences and meteorological factors including temperature and relative humidity. The model was validated by the history data and to be proved with high precision.

Key words: Gansu Province, Gansu Province, Potato Late blight, Grades of meteorological condition