Aiming at the problem that acetaminophen dimer impurities are often detected in the detection of acetaminophen raw material by high performance liquid chromatography, resulting in unqualified quality of acetaminophen and rework, the removal method of dimer impurities in the refining process of crude acetaminophen was studied, the reaction solvent, reaction temperature, reaction time and antioxidants in the refining process of acetaminophen were systematically investigated. The experimental results show that the reaction solvent was ethanol, the reaction temperature was 80 ℃, the reaction time was 0.5 h, and sodium pyrosulfite or insurance powder was used as antioxidant, the content of acetaminophen dimer impurity was significantly reduced, the purity of acetaminophen was improved, and a theoretical basis for improving the quality of acetaminophen was provided.