Abstract: Water and fertilizer has become the main restrictive factors of dryland agriculture development at present. In the arid and semi-arid area, the study about irrigation and nitrogen supply on photosynthetic characters and yield of crops can provide some theoretical guidance for high yield, stable yield in dryland crop. The effects of irrigation and nitrogen application on photosynthetic characters and yield of broomcorn millet was studied in a pot experiment. ‘5283 huang’ and ‘Jinshu 5’ two varieties of proso were experimental materials. Two factors including 3 irrigation levels and 3 nitrogen fertilizer levels were set up. The results indicated that, chlorophyll content, Fv/Fo, Fv/Fm, photosynthetic rate and transpiration rate increased with increasing nitrogen supply at equivalent moisture. The capacity of the leaves for photosynthesis was enhanced. In different treatments, photosynthetic rate, Gs concentration, Fv/Fo and Fv/Fm increased first then decreased with the growth period increased, changing trends were low-high-low, jointing stage was reached to the maximum value. Chlorophyll content, transpiration rate, stomatal conductance increased with the growth period increased, heading stage was reached to the maximum value. Degree of victim about the treatments under severe moisture stress was significantly higher than the other moisture treatments. Degree of victim about the treatments that had no nitrogen fertilizer were significantly higher the other amount of nitrogen, and ‘Jinshu 5’ were more sensitive to water and nitrogen. Under severe water stress and moderate water stress, adverse the nitrogen fertilizer supply could ease drought stress. At the same time, adverse the amount of water could improve photosynthesis of leaves of proso, delay leaf senescence, conducive to crop to maintain photosynthesis in photosynthetic larger area and longer time in areas where lack of nutrients, it could also improved kernel characteristics and increase grain number and increased production.