The synthetic method for 4-(2-phthalimidyl)benzoyl chloride (PIB - Cl) is investigated in this paper. Pre-treatment methods are made better to remove the harmful impurities in the solvents. Dangerous and expensive metal sodium, as a water-absorber and anti-oxidizer in the synthetic process , is replaced with solid potassium hydroxide. The chloridization time is optimized with high performance liquid chromatography. Activated carbon is used to improve the separation and purification for crude product. As a result, the synthetic productivity is raised from 29% to 41.5%. This method, with the higher productivity and lower cost price, is easy to operate and master.