Abstract: The study aims to provide an important basis for IMH020 production process and quality control and develop an HPLC method for the determination of related substances in IMH020. The analysis was performed on a Waters Symmetry C₁₈ column (250 mm × 4.6 mm, 5 µm). The mobile phase A was acetonitrile and the mobile phase B was water-0.2% glacial acetic acid solution with isocratic elution. The flow rate was 1.0 mL·min^-1 and the column temperature was maintained at 30 ℃. The wavelength was 270 and 300 nm. The injection volume was 10 μL. The results show that all the related substances gained a completely chromatographic separation. Good linear relationships of all the related substances (I-1, I-2, I-3a, I-3b, I-4 and I-5) were obtained (r ≥ 0.998 9) and recoveries were in the range of 93.1%-97.8% (RSD ≤ 2%, n = 9). Only I-3a and I-3b were detected below the limit for specified impurities in the three batches of samples, and the largest unspecified single impurity and the total impurities were within the limit. The HPLC method established in this paper is simple, sensitive and accurate, and can be used for the determination of related substances of IMH020.