The invention discloses a high-purity benzene sulfonyl chloride synthetic method.The method comprises the following steps of a sulfonation reaction, a continuous reaction, acid pickling, washing and rectification.The appearance of obtained benzene sulfonyl chloride is colorless and transparent oily liquid, and the yield ranges from 85% to 92%.The high-purity benzene sulfonyl chloride synthetic method is simple in technology and easy to achieve; by means of the reasonable design of the raw material ratio, reaction condition and acid pickling technology, on one hand, the yield of benzene sulfonyl chloride is increased, and the product quality is improved; on the other hand, instant production of large amount of hydrogen chloride gas is avoided, and the safety performance of the technology is improved; in addition, the produced hydrogen chloride gas is made into marketable hydrochloric acid, the working environment is improved, and a certain economic benefit is produced.