Based on the structure of the HIV integrase core domain, dipeptide derivatives, as a type of HIV integrase inhibitor, were synthesized, and their fragmentation pathways were investigated by electrospray ionization mass spectrometry (ESI-MS n ) in conjunction with tandem mass spectrometry (MS/MS). In order to better understand the fragmentation pathways, the MS 2 and MS 3 spectra of the title compound were obtained. The main fragmentation pathways occur by the cleavage of the C-CO bonds between N-(benzothiazol-2-yl)aminocarbonyl and methylene, NH-CO bonds between the NH groups and carbonyl groups. Electrospray ionization was proven to be a good method for the structural characterization and identification of this kind of compound.