The invention discloses spray filter cotton and a preparation method thereof. The spray filter cotton comprises the following raw materials in parts by weight: 50-65 parts of activated carbon, 20-35 parts of diatom mud, 5-10 parts of cellulose, 2-5 parts of plant gum powder, 2-3 parts of macroporous spherical silica gel, 0.5-3 parts of polyvinyl alcohol and 1-3 parts of nano titanium dioxide. Compared with the spray filter cotton in the prior art, by combination of the activated carbon and the diatom mud, the adsorption efficiency is increased, the production of waste liquid is reduced, and the desorption efficiency of the saturated activated carbon is improved.