Abstract: 【Objective】 The study of the grain traits change and its relationship with yield and drought resistance during the change of irrigation amount will provide theoretical basis for drought resistance breeding and water saving cultivation of maize. 【Methods】 Taking the full irrigation water amount of the field as 100%, and set five under-irrigation proportions of 80%, 60%, 40%, 20% and 0%. 10 grain related characters of 10 maize hybrids were determined under 6 water stress treatments, which were used to study the variation trend of grain characters with the proportion of irrigation and the relationship between grain characters and drought resistance. 【Results】 With the decrease of irrigation ratio and the aggravation of drought, the grain weight per plant, 100 grain weight, grain length, grain width, rectangularity, grain color R and grain color G decreased gradually, while the grain thickness, roundness and grain color B increased gradually. The variance analysis showed that the grain weight per plant, 100 grain weight, grain length, grain width, grain thickness, roundness, rectangularity, grain color R and grain color G were significantly different in different irrigation ratios. 【Conclusion】 The grain traits of maize hybrid have obvious response to drought stress. Grain weight per plant, 100 grain weight, grain length, grain width, grain thickness, roundness, rectangularity, grain color R and grain color G could be used as reference indexes for drought resistance identification and drought resistance breeding of maize.