TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (claimed): Compound (I) is prepared by:(A) dissolving equal amount of aromatic aldehyde and p-methylbenzaldehyde into ethanol, where volume/mol ratio of ethanol to aromatic aldehyde and p-methylbenzaldehyde is 3-4 ml/mmol; heating, stirring and backflowing for 0.5-2 hours to obtain reaction liquid; cooling and filtering the reaction liquid; drying the filter cake to obtain an intermediate; dissolving the intermediate with ethanol; adding chloramine T; heating, stirring and backflowing for 3-5 hours to obtain intermediate reaction liquid; removing ethanol and cooling the rest solid; washing for 3-5 times with distilled water; and drying and recrystallizing the filter cake with distilled water and acetone mixed liquid with 1:1-3 volume ratio to obtain recrystallization product A, where mol ratio of intermediate and chloramine-T is 1:3-7 and volume ratio of ethanol and the intermediate is 10-20 ml/1 mmol;(B) dissolving the recrystallization product A and N-bromosuccinimide into carbon tetrachloride at mol ratio of 1:1-1.5; adding initiator benzoyl peroxide at mass ratio of benzoyl peroxide and N-bromosuccinimide of 0.01-0.02:1; heating, stirring and backflowing to obtain reaction liquid; detecting reaction end point of reaction liquid by using thin layer chromatography; removing the carbon tetrachloride; washing the rest solid with ethanol; filtering and drying the filter cake; and recrystallizing the filter cake with mixed liquid of tetrahydrofuran and methanol at volume ratio of 1:1-5 to obtain recrystallization product B, where volume ratio of carbon tetrachloride and N-bromosuccinimide is 3-6 ml/1 mmol;(C) dissolving recrystallization product B in triethylphosphite at mol ratio of 1:1.1-1.5; stirring and backflowing for 3-6 hours at 115-125 degrees C; reducing pressure and removing excess triethylphosphite in the reaction system; adding n-hexane to separate out the solid product; and recrystallizing the solid product with mixed liquid of tetrahydrofuran and n-hexane at volume ratio of 1:1-4 to obtain recrystallization product C; and(D) performing Wittig-Horner reaction by dissolving equal amount of recrystallization product C and aromatic aldehyde into N,N-dimethylformamide to obtain liquid solution; adding 15-30 wt.% of absolute ethyl alcohol solution of potassium tert-butoxide into the liquid solution; stirring and reacting for 5-9 hours at 60-70 degrees C to obtain reaction liquid; cooling and filtering the reaction liquid; and recrystallizing the obtained filter cake with mixed liquid of dimethyl sulfoxide and ethanol at volume ratio of 4-10:1 to obtain compound (I), where volume/mass ratio of N, N-dimethylformamide and recrystallization product C is 10-15 ml/1 g. ACTIVITY - Insecticide.