The invention discloses a foliar fertilizer for enhancing photosynthesis of flue-cured tobacco and a preparation method for the foliar fertilizer. The foliar fertilizer comprises nutritive substances and functional substances, wherein the nutritive substances comprise 31-50 parts by weight of potassium sulfate and 31-56 parts of potassium dihydrogen phosphate, and the functional substances comprise 5-10 parts by weight of organic acid, 5-10 parts of solid organosilicone surfactant, 2-3 parts of minor elements, 0.1-0.9 part of medium elements and 0.1-0.9 part of chelated rare earth. The foliar fertilizer for enhancing the photosynthesis of the flue-cured tobacco and the preparation method for the foliar fertilizer, provided by the invention, have the aims that the chlorophyll content, light energy absorption efficiency and photosynthetic enzyme activity are further improved, thus, the photosynthesis of the flue-cured tobacco is enhanced from a plant physiology aspect, the accumulation of carbon nitrogen metabolism and secondary metabolism products of tobacco plants is promoted, and the improvement on hierarchic structure and quality of tobacco leaves is facilitated.