|Abstract:To establish a high performance liquid chromatography （HPLC） method to determine the content of bacteriostat s in the Ocular Extractives Eye Drops, Diamonsil C18（4.6×250 mm，5 μm）column was used, with gradient elusion by 1% triethylamine solution (pH3.0) (mobile phase A) and methanol (mobile phase B). The detection wavelength was 256 nm, the column temperature was 40 ℃, and the flow rate was 1.0 mL/min. Under these conditions, the three bacteriostats of methylparaben, ethylparoben and chlorhexidine acetate have good resolution. The bacteriostats have good linear relationship between the peak area and the concentration in the concentration range of 0.1～80 μg/mL（r＞0.9991）.The recoveries were 97.2% to 104.1%, and the RSD was 0.8% to 1.2%. The content of bacteriostats in five batches of Ocular Extractives Eye Drops were all less than 10% of the prescription amount. It was found that the activated carbon used in the production process has strong adsorption effect on the bacteriostat, and the lower the temperature, The higher the concentration of activated carbon, the stronger the adsorption of bacteriostatic agent. The adsorption capacity of activated carbon for different bacteriostatis is: chlorhexidine acetate > ethylparoben > methylparaben. The results show that the established HPLC method is easy to operate, high sensitivity and good repeatability. It can be used to quickly and accurately determine the content of bacteriostat in Ocular Extractives Eye Drops. In addition, this study reveals for the first time the effect of the impurity removal process on the bacteriostat in the production of Ocular Extractives Eye Drops. It is not suitable for the use of activated carbon to remove impurities before adding parabens and chlorhexidine acetate bacteriostats. It provides a new guiding basis for its production quality monitoring and improvement.