In order to evaluate the effect of foliar application of some chemicals on antioxidant enzymes activity and chlorophyll fluorescence of sunflower in different irrigation conditions and to identify compounds effective in reducing the adverse effects of drought stress, this experiment was conducted at the Agricultural Research Center of Hamedan, Iran, during two years (2015-16). Three irrigation and six foliar application treatments were evaluated in a split plot experiment based on randomized complete block design with three replications. Irrigation treatments consisted of 60, 80 and 100% plant water requirement and foliar application treatments included: abscisic acid 40 M, Selenium 20 mg/L, Salicylic acid 500 M, SNP 100 μM, Glycine betaine 100 mM and control. The results showed that with irrigation water decreasing, the activity of superoxide dismutase, peroxidase and catalase enzymes increased significantly, while the maximum photochemical efficiency of photosystem II and grain yield decreased. The interaction effect of irrigation × foliar application on the activity of antioxidant enzymes and grain yield was significant and on chlorophyll fluorescence was not significant. In deficit irrigation treatments, foliar application of all chemical compounds significantly increased the activity of antioxidant enzymes compared to control treatment. Application of salicylic acid increased the maximum photochemical efficiency of photosystem II and grain yield, at all irrigation conditions. Under 60, 80 and 100% irrigation conditions, salicylic acid application increased grain yield by 24.3, 10.1 and 4.9% respectively.