An experiment in the split plot factorial design using the randomized complete block design was conducted in Damghan, Semnan Province, Iran in the cropping year 2012-2013 to study the effects of irrigation cessation (based on the phenological stages of the plants) on physiological characteristics of forage millet cultivars. The treatments included three irrigation levels (the control with full irrigation, irrigation cessation when flowering started, and irrigation cessation when flowering ended) in the main plots, and applying nitroxinbiofertilizer (+) and not applying nitroxinbiofertilizer (control) and forage millet cultivars (Bastan, Pishahang, and Isfahan) in the subplots. The maximum water-soluble carbohydrates contents were observed in the cultivar Bastan (8.91%, respectively), the highest contents of fiber and water (74.17 and 48.83%, respectively) in the treatment of irrigation cessation when flowering started, and the largest proline concentration (1.90 mol/g-1ww-1 in the treatment of irrigation cessation when flowering started. Millet tolerated high levels of drought under conditions of irrigation cessation and Nitroxin, as a biological fertilizer, was useful in producing a good quality crop. The very rapid growth of millet, its short growing season, drought tolerance, unique feature with regard to harvest time, and its response to nitroxinbiofertilizer can help to expand its cultivation in arid and semi-arid regions of Iran.