Developing its newly acquired territorial sea is essential for Macau’s sustainable development while facing the truth that it is also an emerging field of strategic planning of the Special Administrative Region Government. Since the planning of the territorial sea should inherit the ideas of sustainable urban planning，this article focuses on how to optimally manage the territorial sea to resolve the side effects caused by the city’s rapid economic development in the past decade. Comparing policy directions and management principles of marine development of developed countries，the reality of Macau is comprehensively assessed. This article argue that although some of the conditions are still immature，Macau has sufficient capacity to fulfill its ambition in marine development. Furthermore，for the purpose of maximizing the economic，social and ecological benefits，in addition to financial and technological considerations，measures are proposed for a sustainable development of Macau’s territorial sea.