The invention discloses an antitranspirant foliar fertilizer and a preparation method thereof. The antitranspirant foliar fertilizer comprises the raw materials of copper sulfate, ethylene diamine tetraacetic acid, monopotassium phosphate, zinc sulfate, ferrous sulphate, manganese sulphate, ammonium molybdate, composite rare earth, boric acid, sodium dodecyl sulphonate, urea, fulvic acid, hexanoic acid 2-(diethylamino) ethyl ester, compound amino acid, magnesium sulfate, calcium nitrate, ethylene diamine tetraacetic acid, microbial agent, azone and ammonia water. The antitranspirant foliar fertilizer provides nutrient elements and microbial agents which are required by the growth of plants, the rare earth and amino acid and other beneficial elements, can promote the growth of the plants, improve the yield, the quality, the stress resistance of the plants and the absorbing and operating capabilities on trace elements, simultaneously can effectively reduce the transpiration of the plants and is applied to afforesting in arid regions.