The invention discloses foliar fertilizer. The foliar fertilizer comprises boric acid, potassium nitrate, epsilon-polylysine, polyacrylamide, ammonium molybdate, butanedioic acid, trace elements, sodium nitrophenolate, water and chelating agent. The foliar fertilizer contains multiple trace elements such as zinc, boron, copper, iron, manganese and molybdenum which are necessary for crops. By adopting the foliar fertilizer, the application amount of pesticides can be reduced, the cost is reduced, the development of the crops is promoted, and the utilization rate of photosynthesis is increased. Experiments prove that the foliar fertilizer is capable of promoting the adsorption of carbon, hydrogen and oxygen and preventing and treating diseases and insect pests.