In order to investigate the effect of levels of drought tension and nitrogen on yield and qualitative  and physiological traits of potato, this experiment as split plots was carried out  based on randomized complete blocks design, with three levels of drought tension S₁ (control, providing 100 percentage water requirement), S₂ (providing 75 percentage) and S₃ (providing 50 percentage of water requirement of potato after emergence to the end of the growing period) as the main factors and four nitrogen fertilizer treatments  N₁ (providing 100 percentage fertilizer requirement), N₂ (66 percentage), N₃ (33 percentage) and N₄ (without applying nitrogen fertilizer) as the sub factors in Agriculture and Natural Resources Research Center of Chahar Mahal va Bakhtiari province. In this experiment maximum tuber yield gained from without tension treatment (S₁) by the amount of 55/9 tons per hectare that had no significant difference at five percent level with S₂ treatment but S₃ with significant difference than two mentioned treatments, produced the average yield 31/7 ton per hectare. N₁ and N₂ treatments produced the highest tuber yield without statistically difference at five percentage level, but lack of nitrogen consumption (N₄) led to the lowest tuber yield (38/7 ton per hectare). Generally, in S₂ and S₃ tension levels, N₂ treatment caused access to the maximum tuber yield. Due to the reduction of tuber yield in S₂ and S₃ treatments within the highest nitrogen consumption level (N₁), the interaction between drought tension and nitrogen on tuber yield was significant at one percentage level.