In order to study the effect of deficit irrigation and foliar application of potassium di-hydrogen phosphate on physiological characteristics of winter wheat (Triticum aestivum L.) cultivar Alvand, a split- plot experiment in a randomized complete blocks design with three replications was conducted in 2008- 2009 season at the Yasooj Agriculture Research Station and Natural Resources. Main plots consisted of three irrigation regimes (full irrigation, cut of irrigation at the beginning of stem rise to the heading and cut of irrigation of heading stage to the end of the growth period), and subplots consisted of five level of foliar application of potassium di-hydrogen phosphate as the zero (foliar application only with water as control), 3, 6, 9 and 12 kg.ha-1 KH2PO4 as foliar spraying. The results showed that the effects of irrigation regimes and potassium di-hydrogen phosphate treatments on all traits were significant. The interaction of irrigation and foliar application of potassium di-hydrogen phosphate on growth and yield traits were significant. Drought stress reduced leaf chlorophyll concentration and phosphorus content, and increased leaf proline and soluble sugar and protein content in grain. potassium di-hydrogen phosphate treatments increased phosphorus, proline and soluble sugars of flag leaf and protein content of seed. Foliar application of potassium di-hydrogen phosphate only under drought stress conditions improves grain yield and growth indicators and in the condition of full irrigation did not observed the significant difference between the levels of foliar application of potassium di-hydrogen phosphate.