The cumulative ecological effects(CEE) of natural resource exploitation and utilization in bay,including accumulative action of the same characteristic effects and cooperative action of different characteristic effects,has brought about rapid changes in productivity and eco-service function of bay ecosystem.Base on fuzzy-correlation analysis,six indices,which are cumulative effects on topographical and geomorphological environment,water dynamical environment,water and sediment quality environment,ecological environment,landscape environment,and the potential incurrence effect on disaster,are selected as indices of CCE in bay.The grey model(GM) of CCE assessment is built and applied to monitor the cumulative effects arising from regular resource exploitation and utilization in bay,and Xiamen Bay is taken as a study case.The result indicated that the six indices of CCE in bay are pro-correlated with intensity of resource exploitation and utilization,while wetland area reduction,coastal topographical and geomor-phological change,water quality and sediment quality deterioration,bio-diversity decrease,landscape pattern break,etc.,are caused mostly by resource exploitation and utilization.And the score of GM assessment on Xiamen Bay in the 50 years is 0.56,which can be taken as a reference background of CCE in bay.This result of CCE has led to changes in the structure of resource and environment system in bay to a certain extent,consequently,the intensity and frequency of disaster and potential loss is increasing,the productivity and eco-service function of natural ecosystem is impaired,and the sustainability of development will be limited eventually.It is suggested that pattern of eco-city planning should be referred to and rational distribution of eco-source,eco-patch and eco-passage shoule be practised so as to prevent the occurrence of ecological desert in the sea sector due to constant increase in resources utilization.