Abstarct: The free radicals amounts are increased due to drought stress and subsequently they harm plant. The plant protects itself by changing antioxidants content (Xs) and scavenging the free radicals (resisting the drought-resulted oxidative stress). This protection is reflected in traits like plant growth (Ys). By maximizing Ys in relation to Xs, the combination of Xs with possible highest Ys can be obtained. This optimization comes from the relations of Ys with Xs under drought stress conditions and alleviators application including the plant ultrasonication and spermin foliar application. This experiment was aimed to do the mentioned optimization for Mung Bean (Line VC1973a). The treatments in a pot experiment located in an open filed were irrigation interval of one (control), 2, 3, and 4 days. In flowering stage, the activity of enzymes catalase, superoxide dismutase, and guaiacol peroxidase was measured. After plant maturity, the harvest index and biomass (Ys) were also measured. Then, using Matlab software and the resulted function, the amount of Xs, for which the highest Ys is obtained, was calculated. baxsed on the results, the optimum concentration of enzymes catalase, superoxide dismutase, and guaiacol peroxidase for gaining the maximum drought tolerance was 0.956 μmol H2O2 g−1 FW, 24.23 μmol H2O2 g−1 FW, and 21.23 AU g−1 FW, respectively. The farm experiment was conducted in one year and 2 locations (Gonbad Cavous Agriculture Research Station and Maraveh Tappeh Agriculture Research Station) in Golestan province. The experiment was as split factorial on the basis of the randomized complet block design with 3 replications. The main factor, i.e. drought stress, included conventional irrigation interval, (7 days interval; control), medium stress (11 days interval), and intense stress (15 days interval). The sub factor was ultrasonication and non ultrasonication, and also the foliar application of one milimolar spermin and non application (water spraying) at flowering initiation stage. In milk stage of grain filling, the leaf content of antioxidants polyphenol oxidase, ascorbate peroxidase and flavonoids (Xs) was measured. Afer plant maturity, the grain yield and grain protein content (Ys) were measured. Using Matlab software and considering optimum structure of neural network, the amount of Xs, for which the highest Ys is obtained, was calculated. The optimum concentration of polyphenol oxidase, ascorbate peroxidase and flavonoid was equal to 0.32 nmol.minute−1.g−1 FW, 0.6 nmol.minute−1.g−1 FW, and 3.5 mg. g−1 FW, respectively.