The objective of this experiment was to study the characteristics of grain dehydrating rate of different heterotic groups and to select the excellent inbred lines with fast grain dehydrating rate, providing the suitable for mechanization of maize hybrids. In this study, 173 maize inbred lines were used as experimental materials. The drying method was used to determine grain dehydration rate, a genome-wide scan was performed on the material by using 210 pairs of SSR markers covering maize genome, and the population structure of these materials was revealed by Structure V2.3.4. The main results were as follows: The clustering analysis showed that these maize inbred lines could be divided into 5 heterotic groups which are PB, LRC, Reid, Lancaster and Tang SPT group, the grain dehydration rate was striking difference in different inbred lines, and it also had significant correlation among husks, cob and grain moisture content; Lancaster has the fastest average dehydration rate (0.92%) 40 days after pollination among them, the others in order was Reid 0.85%, LRC 0.82%, PB 0.76%, TangSPT 0.56%. The grain dehydration rate was striking difference in different inbred lines, and it also had significant correlation among husks, cob and grain moisture content.