| In this study, the high temperature environment at the late stage of maize grain?dehydration in the South Area of Middle Reaches of Yangtze River was used to explore the characteristics of different stages of dehydration rate of maize cultivars with different dehydration rates , especially in the later stage, in order to provide theoretical guidance for breeding and screening maize varieties with fast dehydration. In 2018, three varieties of Xianyu 335 (XY335), Denghai 605 (DH605) and Zhengdan 958 (ZD958) with different dehydration rates were used as materials, planted in Changsha on three sowing dates. The characteristics of dehydration of maize grain at different stages and the relationship between grain dehydration and filling and meteorological factors were analyzed. The results showed that the dehydration rates of the three varieties sown at three different times all increased firstly and then decreased, further followed a rapid increase/rise at the later stage. The rate of grain dehydration before and after the rapid rise of the late stage showed different characteristics. We took the starting point of the rapid increase of the grain dehydration rate in the later period as the separation point, the early stage was the T1 stage, and the later stage was the T2 stage. At the T1 stage, the grain dehydration rate was significantly positively correlated with the grain filling rate (r=0.845**), but no significant correlation with meteorological factors, showing physiological dehydration characteristics; T2 stage, grain dehydration rate were significantly positively correlated with temperature-related meteorological factors and average sunshine hours, and significantly negatively correlated with rainfall, showing net dehydration characteristic. The difference of grain dehydration rate among varieties was mainly reflected at the later stage: i.The grain dehydration rate of XY335 and DH605 were higher than ZD958 at the later stage; ii. When the grain moisture content was used as the evaluation scale, the dehydration rate of XY335 and DH605 increased rapidly earlier than ZD958 at the late stage. The results showed that grain dehydration rate of maize at the later stage was affected by genotype and meteorological factors, the varieties with low moisture content at harvest stage had the characteristics of earlier rapid dehydration and faster dehydration at the later stage.