Vietnam sea port system and the only Cambodia sea port of Shihanoukville have been much developed, particularly in geographical coniext, new port construction, improvement of port procedures and etc.. As a result, recently there has been a dramatic increase of throughputs as well as the number of ships calling at the big sea ports in Indochina Peninsula. Economic benefits are clear. However, environmental problems in the big sea ports have more and more serious due to environmental management system being not invested enough. Environmental pollution with oil and grease, heavy metal, TBT with increasing concentration, accidents of ship collision, oil and chemical spills and etc. have taken place in almost these ports. Response to the degradation of the environment in big ports of Vietnam (Hai Phong, Da Nang and Vung Tau) and Cambodia. several scientific instruments for port environmental management have been proposed based on studying similar instruments applied in European sea ports and other parts of the world, including: Port Environmental Accot{nting, Self-Diagnostic Environmental Performance (SDEP) and 17 steps to implement Environmental Management System (EMS) for sea ports. These scientific instruments were applied as pilot sites in Hai Phong (Dinh Vu Port), Da Nang, Vung Tau and Shihanoukville, supporting port managers and actors to effectively implement their environmental management tasks. In the meantime, publications on these instruments are widely distributed and able to apply to other ports.