Ecosystem health is a new field in ecology and environmental management and it is about fostering a new integrative science. Lake ecosystem health refers to a state of a lake both supplying services for people and maintaining its function and complexity. Assessmenl on lake ecosystem health is the basis of lake environmental management and ecosystem control, so it is important to learn the ecosystem health and spatial differentiation characteristics of a lake. In this case study for Lake Taihu, a large shallow eu-trophic lake, an attempt to apply exergy, structural exergy, ecological buffer capacity and trophic state index to the assessment of the lake ecosystem health was presented. The results revealed there was different ecosystem health to some extent in each area of Lake Taihu through cluster analysis. The ecosystem health of East Lake Taihu was the best among the different areas of Lake Taihu. The ecosystem health of the east part near ihe bank and Lake Gonghu was better. The ecosystem health of the center part and the west part of Lake Taihu was worse. That is to say, the ecosystem health of the east part was better than that oi the west part in Lake Taihu, and moreover, the ecosystem health in different areas of Lake Taihu descended from the southeast part to the northwest. The results will give some advice for environmental management of Lake Taihu and can be used to set up the standard for evaluating ecosystem health of shallow eutrophic lakes.