To establish a new HPLC method for the determination of the related substances in tranexamic acid injection by screening new type of HPLC columns，which can avoid the use of ion pair reagents in current methods and reduce salt concentration.

The method was carried out using a Thermo Mixed-mode WCX column (150 mm×4.6 mm，5 μm)，the mobile phase consisted of 10 mmol·L^-1 sodium dihydrogen phosphate solution (adjust the pH value to 5.2±0.05 with sodium hydroxide solution)-water-acetonitrile （50:5:45），the flow rate was 1.0 mL·min^-1，the column temperature was 25 ℃，the detection wavelength was 210 nm and the injection volume was 20 μL.

The chromatographic peaks of tranexamic acid and its four impurities B，C，D and E were all separated. Good linear relationship was shown between the concentration of all the five compounds and their corresponding peak areas (r≥0.999). The LODs were 0.34，0.50，0.005 6，0.002 1，0.12 μg·mL^-1. The average recoveries (n=9) were 97.4%，100.5%，98.4% and 96.6% with RSDs of 3.9%，0.24%，0.52% and 1.4%，respectively. The test solution and standard solution were all stable within 22 h. The detection results of 5 batches of tranexamic acid injection showed that the number of unspecified impurities and the total impurities content by using the new method were better than the current ChP method.

The established method is specified and sensitive. Good separation can be achieved with low concentration of phosphate. Its applicable to the determination of related substances in tranexamic acid injection.