The invention discloses a method for preparing nanometer titania. The method comprises the following steps: uniformly mixing tetrabutyl titanate and absolute ethyl alcohol according to a volume ratio of 1:(2.5-3.5), thereby obtaining a solution A; mixing and stirring glacial acetic acid, absolute ethyl alcohol and distilled water according to a volume ratio of 1:(3.5-4.5):(1.1-4), adding hydrochloric acid, regulating the pH value to be less than or equal to 3.5, and preparing a liquid B; adding the solution A and the liquid B into a water bath at the temperature of 25-35 DEG C according to a volume ratio of 1:1.1, pouring the solution A into the liquid B while stirring, continuously stirring the obtained mixed solution for at least half an hour, heating in a water bath at the temperature of 40-60 DEG C, thereby obtaining white gel after 2 hours; airing the gel in a fuming cupboard, adding the gel into a muffle furnace, preserving the temperature for 2-4 hours in an environment of 400-600 DEG C, thus obtaining a solid, grinding, thereby obtaining the powder, wherein the powder refers to the nanometer titania. The method has the advantages that the preparation conditions are wide, and the method is easily applied to industrial production.