The invention specifically relates to a bioorganic water-soluble foliar fertilizer prepared with high activity organic acids as carriers and a preparation process thereof, belonging to the field of manufacture of agricultural means of production (fertilizers). The process for the foliar fertilizer is as follows: mixing fulvic acid, molasses concentrate, acetic acid and water according to a certain mass ratio, pouring the mixture into a reaction vessel, carrying out stirring, adding diethylaminoethyl hexanoate, in which the weight of the organic acid solution is 0.29 to 0.31% after deduction of water, 35 to 44% of potassium sulfate, 33 to 40% of monoammonium phosphate, 41 to 50% of urea, 12 to 18% of sodium octaborate and 0.58 to 0.62% of compound sodium nitrophenolate, carrying out isothermal stirring, allowing the temperature of the liquid in the reaction vessel to drop to room temperature and packaging the liquid foliar fertilizer. Organic acids in the foliar fertilizer promote and complement each other, which enables crop leaves to highly effectively adsorb the foliar fertilizer and enables high efficiency infiltration, rapid absorption and a high utilization rate of active components to be realized.