The process of synthesizing 4-N, N-dimethylaminothiobenzoic acid (DMATBA) with 4-N,N-dimethylaminobenzoyl chloride and NaHS as raw materials was studied, involving the influence of the type of reaction solvent, reaction concentration, n (NaHS): n (4-N,N-dimethylaminobenzoyl chloride) feed ratio, reaction time, reaction temperature and n (NaHS): n (HCl) dosage ratio on the yields of the product. The effects of solvent type, reaction concentration, n (NaHS) : n (4-N, N-Dimethylaminobenzyl Chloride) feeding ratio, reaction time, reaction temperature, n (NaHS) : n (HCl) dosage ratio of on product yield were investigated. Experimental results show that the best synthesis process in this screen involved reaction solvent DMF, reaction concentration 1.0 mol/L, n (NaHS): n (4-N,N-dimethylaminobenzoyl chloride) = 2:1, reaction time 2.5 h, reaction temperature 25 oC, n (NaHS): n (HCl) = 1:1 (PH = 3); after acidification, extraction, and vacuum distillation, the total yield of DMATBA can reach 82.1%, and the purity is 93.6%.