The invention discloses a waterborne residual rust antirust coating and a preparation method thereof. The waterborne residual rust antirust coating is prepared from styrene-acrylic emulsion, water soluble epoxy resin, water soluble acrylic resin, iron oxide red, graphene, zinc oxide, barium sulphate, transforming agents, a transformation accelerator, a levelling agent, a defoaming agent, a dispersing agent, a thickening agent and water. The waterborne residual rust antirust coating contains no organic solvent, is environment-friendly and pollution-free, has the characteristic that bottom and surface are combined and has an excellent physical and chemical antirust and rust transforming function, is applicable to rust protection of the surface of steel with rust, a hard oxidation skin layer or an oil paint film and is also applicable to rust protection of the surface of rust-free steel, the preparation method is simple, construction is easy, two transforming agents are complexed in the waterborne residual rust antirust coating, so that a binding force between the waterborne residual rust antirust coating and rust is increased, the waterborne residual rust antirust coating can be directly brushed and coated on the surface of rusty steel and is applicable to multiple construction ways such as spraying, brushing and showering, the coating cost is low, and the rust protection requirements of urban road facilities, bridges, oil and gas pipelines, engineering mechanical equipment, ships and the like can be met.