OBJECTIVE： To establish a method for the determination of related substances in yunsintinib ditosylate active pharmaceutical ingredient. METHODS： HPLC was performed on the column of Waters Symmetry C18 with mobile phase of methanol-0.01 mol/L ammonium acetate solution （gradient elution），flow rate was 1.0 mL/min， the detection wavelength was 240 nm， column temperature was 40 ℃，and injection volume was 10 μL. RESULTS： Under the chromatographic conditions， the main peaks and each impurity peak were well separated； The linear range of impurity A，B，C and yunsintinib ditosylaie were 0.25-2.0 μg/mL （r≥0.999 0）；the quantification limits of impurity A， B and C were 0.5， 0.5 and 2.5 ng， respectively； RSDs of precision， stability and reproducibility tests were lower than 1.0％； recoveries were 97.9％-102.6％ （RSD＝1.4％，n＝9），95.1％-107.7％（RSD＝4.2％，n＝9），95.8％-107.5％（RSD＝4.1％，n＝9）， respectively. CONCLUSIONS： The method is specific and simple， and can be used for the determination of related substances in yunsintinib ditosylate active pharmaceutical ingredients.