The synthesis of sodium 4-methylbenzene sulfinate was investigated by using sodium sulfite deoxidization process from the starting material 4-methylbenzene sulfonyl chloride and the contents of product were analyzed by UV-spectrophotometric method. The aqueous sodium sulfite which used as substrate was added dichloromethane solution containing 4-methylbenzene sulfonyl chloride, at the same time , the pH was controlled by adding dropwise 10% sodium hydroxide solution in the reaction process. The optimun reaction conditions were shown as follows: n(4-methylbenzene sulfonyl chloride)/n( sodium sulfite)=1:1.09, reaction temperature 85℃, reaction time 1h, m(water)/m(4-methylbenzene sulfonyl chloride)=10, pH=7.6,with a yield of 89%.