Abstract: With dramatic development in the coastal zone of the Dashentang oyster reef marine special reserve in Tianjin, its ecological environment has been facing a serious threat. To describe the accurate and comprehensive condition of ecosystem health in this region, a new ecosystem health evaluation system is constructed in this study fully considering its bioaccumulation of heavy metals by oysters, vulnerability of ecosystem, and high impact of harvesting on the sustainable growth of oysters. And its ecosystem health is evaluated and examined using a comprehensive fuzzy model. The results show that the biological and fishing system in this fast developing region is unhealthy, although its benthic substrate and water quality are in good condition. In temporal and spatial distributions, the ecosystem heath tends to improve from near-shore to off-shore and has been getting better overall over time. This ecosystem health evaluation system is an improvement and supplement to the existing system.