Abstract: AimTo identify the components of acetylleucomycin and its hydrolytic products by LC-MS. Methodsacetylleucomycin was separated on a Diamonsil C₁₈ column with 0.1 mol·L^-1 ammonium acetate-acetontrile (35∶65) as mobile phase. The LC-MS was equipped with an electorspray ion source (ESI), which was set at the positive ion mode, and the mass spectra of each component in chromatogram were obtained with difference cone voltage. ResultsThe components of acetylleucomycin and its hydrolytic products can be separated by HPLC. The components were identified according to the molecular weight and its major mass fragment ions. The major components identified in domastic acetylleucomycin were acetylleucomycin A₄, A₅; acetylleucomycin A₁, A₃; acetylleucomycin A₆, A₇, and acetylleucomycin A₁₃. The hydrolytic products of acetylleucomycin were not kitasamycin, but some non-complete hydrolytic product. ConclusionThe method is rapid, sensitive and specific. It’s suitable to application in the fields of multi-components antibiotics analysis.