Abstract: Ergothioneine (EGT) is a rare amino acid in the nature, studies have demonstrated that EGT can act as a natural antioxidant, it is an important active substance found in fungi and various animal tissues. The article used the foreign patents synthetic route which used L-histidine methyl ester dihydrochloride as the initial materials, added benzoyl chloride、concentrated hydrochloric acid etc, by in THF and methanol as the solvents, used multi-step reaction, in order to obtained target ergothioneine. We tried to study effect that different condition in the experiment,and reaction product of each step as well as qualitative measurement by Infrared spectrometer and NMR spectrometer. The analysis of product by series different conditions showed that: the temperature was a big factor in the experiment. Neither the high temperature nor the low temperature the product was impure. On the other hand, the scale when we added the auxiliary material was a factor also, the wrong scale made materials dissolved unsuccessful, it made the reaction couldn’t succeed.