Abstract: Continuous rain during florescence has direct impact on the high and stable yielding of summer maize, while the study of disaster risk zoning can provide basis for the management of disaster risk. By using the daily weather data in the period from heading to spinning stage of summer maize and the yield data of summer maize in Henan Province from 1961 to 2010, this paper statistically calculated the average occurrence frequency and scope of continuous rain during the florescence of summer maize, established the series of disaster risk intensity of continuous rain, and extracted the yield loss rate caused by continuous rain with the method of Lagrange’s interpolation. Finally, the risk zoning index for continuous rain was set up to make zoning of continuous rain during florescence of summer maize in the Province. The results showed that the relatively low risk area of continuous rain during the florescence of summer maize with a risk index below 0.25 was mainly distributed in the most part of north of Yellow River, local part of middle Henan, and east part of Nanyang basin, occupying about 33.3% of the whole Province, whereas the high risk area with a risk index higher than 0.5 was in the north part of north Henan and most part of east Henan and south Huaihe River, occupying about 14.8% of the whole Province.