The invention relates to a synthetic method for 2-methyl-4-carbonyl-2,4-diphenyl butyraldehyde. The synthetic method comprises the following steps: firstly adding 1,1-dimethoxy-N,N-dimethyl methylamine into a methylbenzene solution of acetophenone, after stirring and performing a heating reaction, quenching a product with water, and then carrying out extraction, drying and purification to obtain (E)-3-(dimethyl amino)-1-phenylprop-2-ene-1-ketone; slowly dropwise adding acetophenone into a methanol solution of p-toluenesulfonhydrazide to obtain p-toluenesulfonylhydrazone; and carrying out a reaction on (E)-3-(dimethyl amino)-1-phenylprop-2-ene-1-ketone, p-toluenesulfonylhydrazone, copper hydroxide and potassium carbonate in argon shield, and purifying a reaction product to obtain 2-methyl-4-carbonyl-2,4-diphenyl butyraldehyde. The method is wide in substrate application range, the tolerance for various functional groups is high, cheap copper is taken as a catalyst, and the reaction condition is mild; and a synthetic 1,4-ketoaldehyde compound can be easily converted into various useful synthetic structures, and carries an alpha-quaternary three-dimensional center.