Abstract: Although millet hybrids had higher yield than the traditional seeds, there were still some problems in the production when hybrids were used to substitute qualified traditional seeds. Their quality and premature senility were both challenges. Based on the grey system theory, this paper used grey correlative degree analysis to study the yield of 9 samples of qualified millet hybrids and the relations among their main agronomic traits, so as to find the main factors which could solve the premature senility problem. Main agronomic traits were closely related to yield in the following order: growth duration>sprout number per acreage>ear length>grainrates>functional leaves width>functional leaves length>density of secondary ear>grain weight per ear>single ear weight>plant height>code number per ear>number of tillers. The growth duration, functional leaves length and width should be considered as the main factors which had a great effect on premature senility solution. The suitable growth duration could increase ear length and improve the retention capacity of functional leaves, which could prevent premature senility and get high yield of millet hybrids. This study provided a reference for the selection and breeding of new varieties of millet hybrids.