Based on the meteorological data from 15 stations of summer maize producing areas in Henan Province during 1961 and 2015,the water requirement and effective rainfall in the whole growth period of summer maize were calculated,thus,the irrigation water requirement was obtained.The interannual variation and spatial distribution characteristics of summer maize rainfall,effective rainfall,water requirement and irrigation water requirement were analyzed by linear propensity estimation and spatial interpolation method in Henan Province.The results showed that in terms of time distribution,the rainfall and effective rainfall in summer maize growth period had no obvious change,while the water requirement and irrigation water requirement showed significant downward trend from 1961 to 2015.In terms of spatial distribution,the average annual rainfall in summer maize growth period decreased from southeast to northwest,and the average annual effective rainfall decreased from southwest to northeast in Henan Province;the average annual water requirement of western Henan was higher than that of other regions,while the average annual irrigation water requirement of northern Henan was obviously higher than that of other regions.