The invention relates to a methanol gasoline composite additive, and a preparation method and application thereof. The methanol gasoline composite additive is prepared from the following raw materials in percentage by weight: 68 to 72 percent of animal oil, 0.5 to 1.0 percent of plant oil, 0.2 to 0.5 percent of alkylbenzene, 0.1 to 0.7 percent of monoethanolamine, 0.1 to 0.7 percent of diethanolameine, 0.1 to 0.6 percent of triethanolamine, 1.0 to 2.1 percent of isooctyl nitrate, 1.0 to 2.1 percent of isopropyl nitrate, 1.0 to 2.1 percent of ethyl nitrate, 1.0 to 2.1 percent of sodium hydroxide, 1.0 to 2.1 percent of potassium hydroxide and 18 to 22 percent of water. According to the preparation method, the raw materials are sequentially put into a mixing container according to the proportion, and are stirred at the same time; then, the mixing container is put into ultrasonic waves, and agitation is performed for 15 to 25 min; and the composite additive is obtained. The composite additive provided by the invention can be applied to M25 to M60; the corrosion of methanol gasoline on an automobile can be reduced; and the octane value, the blasting point, the combustion heat value, the oil product quality and the power of the methanol gasoline can be improved.