Organic tin coatings have been in use world-wide in recent years, but most of antifouling paints for marine vessels now are still based on the successful use of cuprous oxide. The antifouling paint must release enough copper into sea water by dissolution of cuprous oxide and form a poisonous surface layer which repels the attachment of marine organisms. It is therefore necessary to maintain a steady leaching rate not too low nor too high. A low leaching rate may result in heavy fouling rapidly. There exist some relation between the copper leaching rate and the paint ingredients. If this relation is well balanced, the copper leaching rate will be improved ,and economic benefit be gained. In order to make a comparative study, we have designed a series of pair formulations in our present experimentation.