Abstract: In order to select parental lines with high combining ability and heritability, and breed strong heterosis and high yield grain sorghum, 18 crossing combinations were made by 3 new sterile lines and 6 new restorer lines with incomplete diallel cross method. General combining ability (GCA) effects and special combining ability (SCA) were used to analyze 6 main agronomic traits including the growth period, plant height, spike length, 1000 grain weight, grain weight per spike and yield. The result showed that the general combining ability of sterile line 15512A was higher in spike length, 1000 grain weight and yield, and the relative effect value of these traits was 2.4962, 4.8319, and 2.6174, respectively. The general combining ability of sterile line 15520A was higher in plant height, grain weight per spike and growth period, and the relative effect value of these traits was 6.9927, 5.7449, and 2.1595, respectively. The general combining ability of restorer line 15670, 15652 and 15607 were relatively high. These parental lines could be applied to breeding and production in the future. The order of the ratio of additive genetic variance to genotype variance of the 6 main agronomic traits was: spike length＞ grain weight per spike＞ plant height ＞growth period ＞yield ＞1000 grain weight. In view of yield trait, 15511A×15652 was a better heterotic pattern.