Abstract: OBJECTIVE To study the compatibility between excipients and medicament packing materials by analyzing the related substances and content of enoxacin eye drops. METHODS The related substances and content of 50 batches of enoxacin eye drops were determined by HPLC. Thermo Accucore XL C₁₈ column(4.6 mm×250 mm, 4 μm) was used. The mobile A was 0.025 mmol·L^-1 phosphoric acid solution(adjust with triethylamine to a pH of 3.0)-acetonitrile-methanol(86:9:5), the mobile B was 0.025 mmol·L^-1 phosphoric acid solution(adjust with triethylamine to a pH of 3.0)-acetonitrile-methanol(350:325:325), with gradient elution to determine the related substances in enoxacin eye drops. Accomplished the study on the compatiblity of excipients and medicament packing material according to the influence factor test and accelerated test. RESULTS Polysorbate 80 in the formula could lead to the increase of specific impurities and the total amount of impurities. Light could lead to the increase of the total amount impurities and the decrease of enoxacin. The photodegradation reaction could be reduced by using shading packaging. CONCLUSION Excipients that can increase impurities should be avoided in the production of enoxacin eye drops, and shading materials should be used for packaging.