This research was carried out at Agronomy Department Farm, Faculty of Agriculture, Assiut University, Egypt, to study the effect of water stress, genotypes and their interaction on seed yield and its components of pear millet. A set of twenty genotypes were sown in two experiments i.e. normal and water stress irrigation during 2019 and 2020 seasons. The split block design with three replications was used in both experiments. The results showed that the treatments of irrigation and genotypes and their interaction had highly significant effect on number of panicle/plant, panicle length, and thickness, panicle weight, grain yield/plant and 1000 grain weight. Mainly, the water stress caused a decrease in number of panicle/plant, panicle length and thickness, panicle weight, grain yield/plant and 1000-grain weight by 28.5, 40.6, 37.3, 25.0, 24.7 and 37.1%, respectively, as average of the two seasons. The used pear millet genotypes were classified according to drought susceptible index (DSI) into two groups, the first were tolerant to drought and second one susceptibility to drought. Some of those genotypes different from season to season for reduction and (DSI ). The superior genotypes using DSI were genotypes Nos. 4 and 5 there were tolerant to drought stress for seed yield/plant in both seasons.