Coastal zones cover only 10% of the earth′s surface but are inhabited by over 50% of the world′s population and become regions with diverse, essential, and extensive economic activities. In China, to resolve the conflict between economic development and land shortage, reclaiming land from sea has become increasingly intense in many coastal cities from the 1980s. While expanding land areas for economic production of various types, construction of factories and dwellings, and increasing economic benefits, sea reclamation activities have nevertheless caused a series of negative effects on coastal ecosystems by either displacing or destroying them. Unfortunately, some decision-makers and others, such as developers, often pay more attention to short-term direct economic benefits while ignoring ecological damages and environmental degradation from sea reclamation projects. To account for those damages, therefore, it is necessary to monetarily evaluate the losses of coastal ecosystem services induced by sea reclamation activities and to integrate that information into the planning, exploitation and management decisions affecting coastal zones. Tong′an Bay, located to the north of Xiamen Island, has a sea area of 89.9 km2, featuring a half-closed sea bay with a narrow entrance exemplifies the assessment of those damages. Since 1950, the reclamation projects in Tong′an Bay have added 33.65 km2 of land. As a result of the urbanization of Tong′an district and the development of the West Side Economic Zone of the Taiwan Strait, the sea reclamation demand in Tong′an Bay continues to exist. This paper focuses on the four sea reclamation planning projects to be developed in Tong′an Bay, Xiamen. Based on the analysis of the adverse effects of sea reclamation projects on coastal ecosystems, and considering the characteristics of coastal ecosystem services, the paper establishes the monetary valuation models to estimate the losses of coastal ecosystem services associated with sea reclamation projects. The methods for building these models include: Conventional Market Approach, Replacement Value Approach, Experimental Market (Pseudo-Market) Approach, and the Benefit Transfer Approach. These models are applied to the case study of Tong′an Bay, and are used to quantify the losses of coastal ecosystem services likely to be associated with each of four planning projects. The estimated results show that the ecological losses from four planned projects would be: 1.36×108yuan/a, 5.44×108 yuan/a, 6.79×108yuan/a and 1.48×109 yuan/a, respectively, and the ecological losses per unit area would be 68.65 yuan/(m2?a), 70.36 yuan/(m2?a), 72.43 yuan/(m2?a) and 76.84 yuan/(m2?a), respectively. The ecological costs are larger than the project costs and they increase with the sea reclamation area. Based on the valuation results, the relevant recommendations about sea reclamation in Xiamen′s bays are also provided. The conclusions are that, on the one hand, Strategic Environmental Assessment should be carried out within sea reclamation planning in order to minimize the damage on coastal ecosystem. On the other hand, the standard user fee for sea reclamation should be adjusted so that the government can optimally regulate the level of reclamation while safeguarding the sustainable development of the coastal zone.