In order to provide ecological information for public and decision-makers, some ecosystem assessment projects were implemented in the international society. Those cases could be classified into two development directions of ecosystem assessment: One inclined to report the state of ecosystems in an objective way, such as NRC's report and Heinz′s report; the other was prone to link the ecosystems to social-economic system so that concrete policy recommendations can be put forward, such as Millennium Ecosystem Assessment (MA) and Global Environment Outlook(UNEP GEO). After those cases were analyzed comprehensively, some experiences or characteristics about those assessment projects were summarized as follows: (1)Suitable ecological indicators should be identified; (2)Reasonable conceptual framework is the core of ecosystem assessment; (3)In order to put forward policy recommendations, the linkage between ecosystems and social economic systems should be established; (4)Ecosystem assessment should be repeated periodically or irregularly; (5)Stakeholders from government, the private sector, environmental organizations, academia and the general public should be involved. In order to make the assessments contribute to ecological policy-making and the regional sustainable development, the two development directions should be integrated.