An HPLC analytical method was developed to determine the related substances in carbetocin injection. The method was performed on a Waters Xbridge C₁₈ column (150 mm×3 mm, 3.5 μm) with 0.30 mg/mL ammonium acetate-19% acetonitrile aqueous solution as mobile phase A and mobile phase A-acetonitrile (1∶1) as mobile phase B. The detection wavelength was 220 nm. Gradient elution was performed at the flow rate of 0.8 mL/min and the column temperature of 60℃. The method was validated for system applicability, specificity, linearity and range, accuracy, with the results that the 9 impurities of carbetocin injection showed good linearity (R²>0.999) with peak area in their respective concentration range, and that the method had good precision (RSD<5%). This method is suitable for the simultaneous determination of carbetocin and its 9 impurities in carbetocin injection and can provide a theoretical basis for the quality control of the carbetocin injection.