The invention provides magnetic nanometer water-based paint as well as preparation and application thereof. The paint is the paint modified by using superparamagnetic nanoparticles. The preparation method comprises the following steps: mixing the colloid aqueous dispersion of superparamagneticferroferric oxide nanoparticles with raw materials of the paint uniformly in a certain proportion to obtain the magnetic nanometer water-based paint, wherein the magnetic nanometer water-based paint is prepared from 25-75% of emulsion, 15-70% of ferroferric oxide colloid aqueous dispersion, 0.05-0.1% of a preservative, 12-20% of other paint adjuvant and the balance of water. Based on the superparamagnetism of the nanoparticles, the magnetic paint provided by the invention generates strong local induction magnetism only when a magnetic field exists so as to realize magnetism. According to the paint, a painted surface is endowed with a magnetic function, and if the paint is combined with a magnet in use, stable fixation or suspension of an object on a wall can be realized. The magnetic nanometer water-based paint can bring great convenience for life, has important practical value, and is suitable for use at school, home, office and places where objects need pasting and suspending.