The yield of hybrid millet ZZG 3 was significantly higher than that of conventional varieties, which was due to its excellent photosynthetic and physiological characteristics under drought stress. Therefore, the study of its photosynthetic characteristics is helpful to understand the photosynthetic of high-yield hybrid millet growth advantage and utilization breeding technology. Under extreme drought conditions in Dunhuang, the photosynthetic characteristics and material accumulation of hybrid millet were studied by using ZZG 3 and its parents. The results showed that ZZG 3 had significant transgressive heterosis before 3-leaf stag when the growth of nutrients required from grain, and 33.3% higher than parents. At the beginning of filling stage, SPAD value of flag leaf was only decreased 3.56%, but 26.42% and 29.18% in parents, respectively. At the same time, the diurnal variation of net photosynthetic rate（P_n） of ZZG 3 and its parents showed an obvious bimodal curve regardless of drought or not. After drought stress, the diurnal variation of P_n decreased most significantly in female parent, and ZZG 3 showed mid-parent heterosis. However, under drought stress, the WUE of ZZG 3 did not decrease substantially, the double peak increased by 1.03% and -4.46%, the restorer line decreased by 18.83% and 32.39%, while the male sterile line decreased most significantly, reaching 32.39% and 29.04%, respectively. Subsequent research will continue to carry out photosynthetic characteristics of hybrid millet, which established the foundation for breeding more drought-resistant and high-yield hybrid millet.