Abstract: An LC-MS method was established for the identification of the related substances in rivaroxaban. HPLC separation was carried out on an Inert Sustain C₁₈ column(250 mm×4. 6 mm, 5 μm)with linear gradient elution using a mobile phase consisting of 0. 2% formic acid acetonitrile and 0. 2% formic acid aqueous solution. Rivaroxaban and its related substances could be completely separated under the established HPLC conditions. The structures of the related substances were identified by electrospray positive ESI high resolution TOF/MS and MS/MS spectra determination and elucidation, and further verified through reference substances. Fifteen related substances were detected and identified to be three related substances of starting materials, four synthetic by-products and ten degradation products. The established method is useful for the identification of the related substances in rivaroxaban. The results obtained are valuable for its manufacturing control and quality assurance.