Objective : This experimental study was performed to investigate the effect of herbal eye drops, Sean-tang and Coptidis rhizoma on Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa keratitis. Methods : After administering herbal eye drops (Sean-tang, Coptidis rhizoma) on Staphylococcus ausreus, Staphylococcus. epidermidis and Pseudomonas aeruginosa, I measured MIC and the size of inhibition zone. MIC was measured by dropping to $50{mu}{ell}$ according to density(l00%, 10%, 1%, 0.1%). Anti-bacterial potency was measured by the size of inhibition zone with change of volume. Result : On Staphylococcus aureus, Staphylococcus epidermidis, Coptidis rhizoma showed the highest anti-bacterial potency and on Pseudomonas aeruginosa, Sean-tang, Coptidis rhizoma was nor anti-bacterial potency. Conclusions : The present author think that the herbal eye drops, Sean-tang and Coptidis rhizoma can be used to cure Staphylococcus aureus, Staphyloccus epidermidis keratitis and if further study is performed, the use of the herbal eye drops will be valuable and beneficial in the clinical medicines.