Abstract: Based on the “ Exposure- Sensitivity- Ability to adapt" framework, the vulnerability assessment index system was established for Luoyuan Bay ecosystem. The ecosystem vulnerabilities in 3 periods ( 1986 ~ 1990, 2004 ~
2006, 2010 -2012) were studied used the fuzzy comprehensive evaluation method. The results showed that all 3
periods were in "mild-vulnerability". The scores increased in years and Luoyuan Bay ecosystem tended to be incieasingly vulnerable. The evaluate results of 3 subsystems showed that the exposure intensity of Luoyuan Bay eco-
system was increasing and the major artificial stress factors were leclamation areas , port industry developments and
 aquacuhxire density. And tfie sensitivity of Luoyuan Bay ecosystem was obviously intense, the main sensitive factors
were comprehensive index of marine life quality, biological diversity indexes of zooplankton and intertidal benthic.and species and density of fish larvae and eggs. Meanwhile, the adaptive capacity of Luoyuan Bay ecosystem presented a good tendency. This research can provide a reference for the vulnerability assessment of bay ecosystem in 
similar regions.