A UV spectrometric method was established for the determination of main drug content of nafamostate mesilate for injection. First, ultraviolet spectrophotometer was used to determine the concentration absorbance of nafamostate mesilate for injection at 241 nm, then calculate its content. The results show that the linear relationship between concentration and absorbance is good in the ranges of 0～10.0 μg/mL（r = 0.999）, the average recoveries are 100.4%-101.7%, RSD is 0.43%. This method is simple and feasible with good accuracy and repeatability, which can be used for the content determination of the nafamostate mesilate for injection.