Abstarct: Among the limiting factors for plant growth, drought stress is an important non-living factor that limit agricultural production. Today, application of compatible solutions has been considered in reduction the effect of environmental stresses such as drought stress. Ascorbic acid has been special antioxidant effect. In order to analyze the foliar application of ascorbic acid on soybean traits in stress conditions, a trial was carried out at the Department of Agronomy and Plant Breeding of Shahrood University of Technology in 2010. Treatments including stress levels (10, 15 and 20 days interval irrigations) and ascorbic acid foliar application (0, 5, 10, 15, 20 and 25 mM) were organized in split plot experiment on the basis of completely randomized block design in three replications. Water deficit stress reduced leaf and stem dry weight, total dry weight, yield, number of pods and seeds per pod. Of course, of 20 days interval treatment in water stress had a significant effect compared to other irrigation levels. Effect of water deficit on plant height and 1000 seed weight was non-significant. Water deficit stress, specially severe drought increased seed protein and plasma membrane damage and diminished stem diameter, leaf relative water content, percentage of plasma membrane stability, seed protein yield, percent and yield of seed oil and chlorophyll content in leaves. Ascorbic acid spraying, specially 25 mM concentration increased plant height, stem diameter, leaf dry weight, shoot and whole plant, chlorophyll, oil and protein percentage and yield, seed yield and yield components, leaf relative water content and stability of plasma membrane and decreased membrane damage. Leaf weight ratio was increased and the other measured indicators of growth were decreased by sever stress. The intraction between ascorbic acid foliar application with 25 mM concentration and non-stress condition has the highest effect on investigated traits.