Objective : This experimental study was performed to investigate the effect of Coptidis rhizoma extract on Staphylococcus aureus and Staphylococcus epidermidis that induce keratitis. Methods : MIC was measured by flowing to $50{mu}l$ according to density Coptidis rhizoma extract(100%, 10%, 1%, 0.1%). Anti-bacterial potency was measured by the size of inhibition zone with change of volume. Results : 1. MIC on Staphylococcus aureus in Coptidis rhizoma extract was 100%, $50{mu}l$ and anti-bacterial potency increase compare with quantity. 2. MIC on Staphylococcus epidermidis in Coptidis rhizoma extract was 100% & 10%, $50{mu}l$ and anti-bacterial potency increase compare with quantity. Conclusions : The Present author think that Coptidis rhizoma extract must be made a new eye drops.