Abstarct: Wheat is one of the most important crops in the world, but wheat grain yield is reduced by terminal Dehydration stress occurs in the most wheat growing farmlands of Iran. The use of plant growth regulators such as brassinosteroids can protect plants against different environmental stresses such as drought. The aim of this study is evaluate the effect of foliar application of brassinolide on morphological, physiological, biochemical traits, antioxidantenzymes, photosynthetic pigments, grain yield and yield components of wheat genotypes under terminal Dehydration stress conditions. Also, extracting the related genes to brassinolide signaling in wheat (BES1,BRI1) was investigated. A field experiment was conducted as split split plot in a completely randomized block design with three replications at experimental farm of Seed and Plant Improvement Institute, Karaj during 2017-2018 and 2018-2019 growing seasons. Irrigation regimes (normal and cut off after flowering) and four levels of foliar spray of brassinosteroid (0, 0.25, 0.65 and 1 mg-1.L ) were assigned in main plots and subplots, respectively. And sub subplots in the first year was 17 wheat genotypes (1354, 1998, 1399, 1392, 2853, 3506, 3729, 3737, 4056, 4228, Mehragan, Niknejad, Parsi, Roshan, Sirvan, Sivand, Star), and after selection according to yield and drought tolerance indices, in the second year 7 wheat cultivars (3737, 4228, 3506, 4056, Mehragan, Parsi) were cultivated. The results indicated that on one hand, terminal Dehydration stress decreased plant height, number of fertile tiller, flag leaf length and spike length and on the other hand, foliar spray of brassinosteroid increased mentioned traits. Also, terminal Dehydration stress decreased leaf relative water content and cell membrane stability index and increased cell membrane leakage, while application different levels of brassinosteroid increased leaf relative water content and cell membrane stability index and decreased cell membrane leakage. Terminal Dehydration stress increased proline, catalase and ascorbat peroxidase enzymes and decreased protein, but application brassinosteroid decreased proline and increased protein and catalase and ascorbat peroxidase enzymes in two years. Terminal Dehydration stress decreased chlorophyll¬ a, chlorophyll¬ b, total chlorophy ll and carotenoid and application some levels of brassinosteroid increased mentioned pigments. Also, terminal Dehydration stress reduced grain yield and yield components and application brassinosteroid increased mentioned traits. Also, evaluating genes exxpression of signalling pathway demonstrated that although foliar application of brassinolide increased the Dehydration stress tolerance but its signalling pathway is different from known brassinolide signalling pathway. Among studied genotypes, according to drought tolerance indices, genotype 4228 were known as the most drought tolerant genotype and it can be used in further breeding program for drought tolerance.