In pipeline constructions especially for oil and gas, corrosion is a natural phenomenon which cannot be avoided but can be reduced. There are many kinds of corrosion protection can be used in this area and inhibition is one of it. At present inhibitors used commonly from chemical kind. This kind of inhibitor is expansive and toxic. The knowledge of plant substances have opened a new era of inhibitors. Research has proved that inhibitor can be made from plants which are rich in antioxidant and tannin. This research is conducted to see the inhibition mechanism of several plants which are rich in antioxidant and tannin. The plants used as inhibitors in this research are: manikara zapota; garcinia mangostana l., and ipomea batatas. Corrosion test are applied to API-5L in produce water environment. The conclusions of this research show that it is possible to use plants as inhibitor and when it is used as inhibitor every plant has their own mechanism.