Abstract: Para-tert-butylcatechol (4-TBC) is synthesized from catechol and MTBE using sulfuric acid catalyst. The methods of analysis and characterization on reaction process are investigated. 13C-NMR technique combined with gas chromatography (GC) is introduced to characterize the synthesized products. Adopting 13C-NMR technique to analyze the progress of reactions real timely, optimum process parameters can be obtained. The results show that characterizing the product by GC alone is much complex, and it is difficult to distinguish the peaks of impurities. By 13C-NMR method, the chemical shift of various carbon positions in the molecular structure can be determined, thus the reaction mechanism and carbon positions for reactions could be inferred, in a word, the components in product can be distinguished more clearly. Under the conditions of a mass ratio of catechol to MTBE of 1, a catalyst dosage of 6% (based on catechol), a reaction temperature of (120±2) ℃, MTBE adding time of 2.0-2.5 h, at 1.5 h after the completion of adding MTBE, the content of 4-TBC in the mixed product is 84.3%, and a 1.6% of 3,5-DTBC is detected.