Abstract: A UHPLC-Q-Orbitrap/MS method was developed to identify the related substances in apixaban tablets. Complete separation was accomplished with a Waters Xbridge C₁₈ (250 mm×4.6 mm, 5 μm) column by linear gradient elution using a mobile phase consisting of 30 mmol/L ammonium acetate buffer solution (pH 4.50) and acetonitrile. The related substances were successfully characterized through the accurate mass and elemental composition of the parent ions and their product ions determined by electrospray positive ionization high-resolution Q-Orbitrap/MS methods. Under the established analytical condition, apixaban and its related substances were well separated, and 30 related substances were detected and identified by hyphenated techniques in apixaban tablets and their stressed samples. Among them, 11 were known impurities and the rest 19 were unknown related substances identified for the first time in this study. The results obtained are valuable for apixaban manufacturing process optimization and quality control.