The invention relates to a synthesis technology for 2, 4, 6-trimethylbenzene acetyl chloride, comprising the following steps of: putting thionyl chloride, a catalyst and 2, 4, 6-trimethylbenzene acetic acid into a reaction kettle in batches, and controlling temperature to carry out reaction; and after the reaction, distilling (high vacuum) in a heating way in the reaction kettle, and acquiring a final product. The preparation method of the 2, 4, 6-trimethylbenzene acetic acid can comprise the following steps of: carrying out chloromethylation reaction by taking trimethylbenzene, formaldehyde and concentrated hydrochloric acid as raw materials, adding toluene to extract after reacting, and washing to obtain a toluene solution of 2, 4, 6-trimethyl benzyl chloride; taking the toluene solution of 2, 4, 6-trimethyl benzyl chloride and the sodium cyanide as raw materials, adding a phase transfer catalyst, reflowing in a heating way to carry out cyanation reaction, washing by adding water after reacting, distilling oil phase to recover toluene and mesitylene, and rectifying to obtain 2, 4, 6-trimethylbenzene acetonitrile; and hydrolyzing the 2, 4, 6-trimethylbenzene acetonitrile, centrifuging to obtain a 2, 4, 6-trimethylbenzeneacetic acid crude product, and optionally selecting and carrying out the aftertreatment to obtain the 2, 4, 6-trimethylbenzeneacetic acid. The content of the 2, 4, 6-trimethylbenzene acetyl chloride synthesized by the method disclosed by the invention is more than or equal to 98.0%, and the content of the 2, 4, 6-trimethylbenzene acetonitrile is less than or equal to 0.5%.