Abstract: The Huang-Huai-Hai plain is the main production area of summer maize in China, which is also one of the worst-hit drought areas. The loss of summer maize yield caused by drought has seriously affected China’s grain production. Therefore, it is of great significance to clarify the law of drought in this area for the formulation of anti-disaster measures and the guarantee of grain production. Base on the meteorological data of 76 stations from 1981 to 2015 in Huang-Huai-Hai plain was used in this study, the crop water deficit index(CWDI) as the drought index was used to analyze the spatial-temporal evolution characteristics of drought for summer maize in this area. The results showed that the overall changing trend of CWDI in the whole summer maize growth period increased first, and then decreased with the highest drought frequency occurring in sowing-seedling stage and tasseling-milk ripe stage. Drought was getting worse in the summer maize growth period during the period of 2011 to 2015, and southern Hebei, northern Henan and Shandong province exhibited the highest CWDI value. The slight drought was the main drought type in this area in the whole summer maize growth period, the moderate light drought ranked second and the severe and extra severe drought was barely. The frequency of drought in the northern area was higher than that in the southern area, as well as the western area was higher than that in the eastern. The ratio of extra severe drought occurring station was the highest in the sowing-seedling stage, and the ratio of slight drought occurring stations was the highest in the other growth periods.

Key words: Summer maize, Huang-Huai-Hai plain, CWDI, Drought frequency