Land has been widely reclaimed in large area in coastal zones all over the world to relieve the pressure of land shortage,promoting social development and economic growth.Asia has become a focus of land reclamation with the rapid industrialization and urbanization.From the Binhai New Area of Tianjin to the Caofeidian New Area of Tangshan,the undergoing project of land reclamation on the northwest coast of Bohai Bay,China,is the largest in the world.To clarify the environmental issues and benefit sustainable development of the coastal zone,we conducted both retrospective and predictive assessments of the ecological cost caused by land reclamation on the northwest coast of Bohai Bay,China.We calculated the ecological costs of ten aspects of the four ecosystem services,i.e.,supply,regulation,support and culture,with the monetary estimate approach.The results indicate that the ecological cost of the new land reclamation is US$971.9 million from 2000 to 2010 and that the cost will be US$702.1 million from 2010 to 2020.The costs of gas regulation and marine food supply account for the greatest parts of the total value.Suggestions for land reclamation oriented to sustainable development in the study area are put forward,including a rational planning based on the comprehensive evaluation,reducing the amount of land reclamation area,optimizing the structure of the reclaimed land,reclaiming land with the concept of “low impact development” and implementing ecological compensation mechanisms,etc. Land has been widely reclaimed in large area in coastal zones all over the world to relieve the pressure of land shortage, promoting social development and economic growth .Asia has become a focus of land reclamation with the rapid industrialization and urbanization .From the Binhai New Area of Tianjin to the Caofeidian New Area of ​​Tangshan, the undergoing project of land reclamation on the northwest coast of Bohai Bay, China, is the largest in the world. To clarify the environmental issues and benefit sustainable development of the coastal zone, we are both retrospective and predictive assessments of the ecological cost caused by land reclamation on the northwest coast of Bohai Bay, China. We calculated the ecological costs of ten aspects of the four ecosystem services, ie, supply, regulation, support and culture, with the monetary estimate approach.The results indicate that the ecological cost of the new land reclamation is US $ 971.9 million from 2000 to 2010 and that the cost will be US $ 702 .1 million from 2010 to 2020.The costs of gas regulation and marine food supply account for the greatest parts of the total value. Suggest for land reclamation oriented to sustainable development in the study area are forward forward, including a rational planning based on the comprehensive evaluation, reducing the amount of land reclamation area, optimizing the structure of the reclaimed land, reclaiming land with the concept of “low impact development ” and implementing ecological compensation mechanisms, etc.