Abstract: To reveal the Synoptic-meteorological reasons of wheat scab weather pandemic, the author analyzed meteorological conditions and synoptic situation of Jiangsu Province during the period of wheat scab high prevalence in 2003. The results showed that: (1) Frequent occurrence of continuous rain synoptic processes in spring , excessive rain, high humidity, lack of sunlight during the flowering period of wheat, which resulted in wheat scab high prevalence of Jiangsu Province in 2003. (2) The alternation of stable circulation situations of blocking high in Europe and Asia, greatly low whorl in the north and northern ridge and two troughs on 500hpa; the existence of shear lines on 700hpa; the swing in Yangtze valley of quasi-static front on the ground; the water vapor transportation of southwest flow on 850hpa, the water vapor's convergence rise in the low level of Jiangsu area, the promotion caused by the intersection of cold and warm air current to the release of the latent heat, which caused four continuous rainy synoptic processes in Jiangsu Province during the flowering period of wheat in 2003. The findings may provide basis on the short and medium potential trend forecast for the occurrence of wheat scab.