The invention relates to the technical field of asphalt coating production, and in particular, relates to outdoor floor water-based asphalt bottom paint and a processing technology thereof. The outdoor floor water-based asphalt bottom paint is prepared from the following raw materials in parts by weight: modified asphalt, a filler, a film-forming resin emulsion, an emulsifier, a liquid-phase rareearth stabilizer, a film-forming stabilizer, a defoaming agent, an initiator, a UV agent and deionized water. The water-based asphalt bottom paint provided by the invention has good corrosion resistance, low temperature resistance and aging resistance, and can improve the impact strength of outdoor floors. The processing technology comprises the steps: weighing the modified asphalt, adding the modified asphalt into a proportioning device, weighing the film-forming resin emulsion and deionized water, sequentially adding the weighed filler, the weighed liquid-phase rare earth stabilizer, the weighed UV agent, the weighed emulsifier, the weighed film-forming stabilizer, the weighed defoaming agent and the weighed initiator into the proportioning device, stirring, vacuumizing, naturally cooling to room temperature, and finally screening and filling. The process has the advantage that the high-quality asphalt bottom paint can be obtained through quantitative production.