Agricultural water consumption varies drastically with the change of precipitation. Determining the relation among agricultural water consumption in different precipitation years has always been a difficulty. In this article, according to the actual data of precipitation and irrigation water consumption per unit hectare, the ratio of irrigation water consumption at a given precipitation frequency to multi-year average irrigation water consumption (defined as regulation coefficient)is calculated for six irrigation regions. Furthermore, according to the status quo of agricultural development and water resources in Jiangsu Province, the values of regulation coefficient at different precipitation frequencies are obtained. Results show that the maximum regulation coefficient is 1.12 at 70%-80% precipitation frequency, and the minimum regulation coefficient is 0.81 at 95% precipitation frequency;according to planning, the irrigation water consumption in 2020 at 75% precipitation frequency is estimated to be 7 210 m³/hm², and 5 197 m³/hm² at 95% precipitation frequency.