One source of marine pollution is sludge oil from ship activities, which is then spread by currents and winds. Such as the contamination of the Indonesian Bintan Coast by sludge oil that has occurred every year, since 1970, which is thought to have come from the Outer of Port Limit east of the Singapore Strait. The countermeasure carried out by the local government is to clean the coast and collect the Sludge oil. This article is the result of research on pollution prevention. This research methodology uses Doctrinal legal research with a statutory, conceptual and case approach. Based on the results of this study, the solution to overcome pollution at the outer port limit is with the principle of cooperation for littoral states and user states in the Singapore strait based on agreements because the settlement of cases is not easy to prove a causal relationship between pollution and pollutants through scientific evidence. , so that the source of the pollutant cannot be known (unknown). The solution that can be done is to establish the jurisdiction of the outer port limit between the littoral state in the Singapore Strait and apply the principle of cooperation with bilateral or multilateral cooperation agreements between the littoral state and the user state in the Singapore Strait. That this method is more effective and faster in resolution and can avoid conflict. The solution that can be done is to establish the jurisdiction of the outer port limit between the littoral state in the Singapore Strait and apply the principle of cooperation with bilateral or multilateral cooperation agreements between the littoral state and the user state in the Singapore Strait. That this method is more effective and faster in resolution and can avoid conflict. The solution that can be done is to establish the jurisdiction of the outer port limit between the littoral state in the Singapore Strait and apply the principle of cooperation with bilateral or multilateral cooperation agreements between the littoral state and the user state in the Singapore Strait. That this method is more effective and faster in resolution and can avoid conflict.