Abstract: Based on the ACE inhibitor peptides isolated from jellyfish gonads,investigated the synthetic dipeptide Ser-Tyr(SY)conformation changes were by nuclear magnetic resonance(NMR)in the aqueous solution,DMSO solution and methanol. The conformational changes were analyzed by ¹H-NMR spectra and ¹H-¹HNOESY spectra. The results showed that the SY molecules in different solution environment,the conformation also changed. Which was present in an aqueous solution,a free stretching conformation exists. In the methanol solution was the extension of the state as the dominant conformation and associated with the existence of folding conformation. In the dimethyl sulfoxide(DMSO)solution was in a folded,curled state. This study would provide an important theoretical basis for the further analysis of SY molecular structure.