The invention belongs to the technical field of agricultural fertilizers and relates to a foliar fertilizer for wheat. The foliar fertilizer comprises a first-stage fertilizer for a vegetative growth stage of the wheat and a second-stage fertilizer for a reproductive growth stage of the wheat, wherein the second-stage fertilizer contains a flowering stage fertilizer sprayed at a flowering stage and a grain filling fertilizer sprayed at a grain filling stage, and the grain filling fertilizer contains 20-40 parts (by weight) of biogas slurry, 6-12 parts (by weight) of borax, 2-5 parts (by weight) of betaine, 15-20 parts (by weight) of seaweed powder and 1-3 parts (by weight) of glycerine. According to the foliar fertilizer for the wheat, different foliar fertilizers are prepared in view of the vegetative growth and reproductive growth of the wheat, so that the yield of the wheat can be increased by making full use of every stage of growth of the wheat; and particularly, by the use of the flowering stage and the grain filling stage, the flowering stage is prolonged, the success rate of pollination is increased, the grain filling is accelerated, the grain filling rate is increased, the plumpness of grains is greatly improved, the absorption effect of the foliar fertilizer is good, the consumption is low, and the cultivation cost is reduced.