A method for preparing 3,3-dimethylbutyraldehyde. The method includes: providing t-butyl chloride and vinyl acetate as raw materials, conducting a catalytic reaction between the t-butyl chloride and vinyl acetate to yield 1-chloro-3,3-dimethyl butyl acetate in the presence of a catalyst, the weight ratio of t-butyl chloride to vinyl acetate being 1:0.84-0.93; and controlling a temperature at between 100 and 110° C. for conducting hydrolytic disproportionation of 1-chloro-3,3-dimethyl butyl acetate in the presence of the catalyst to yield a mixture comprising 3,3-dimethylbutyraldehyde; and purifying the mixture by distillation to yield 3,3-dimethylbutyraldehyde, in which, the catalyst is aluminum trichloride, p-toluene sulphonic acid, or iron trichloride.