In this study,we assessed the ecosystem service value of the oyster farm in Dapeng Cove,Daya Bay,using the methods and procedures of Millennium Ecosystem Assessment and Technical Directives for Marine Ecological Capital Assessment.Results indicated that,the total ecosystem service value(ESV)of the oyster farm in 2012 was 3 460.52×10⁴ RMB,and the unit ESV was 17.30×10⁴ RMB/hm².The aquaculture production service value(3 158.00×10⁴ RMB)accounted for the largest proportion of the ESV(91.26%); besides,the recreation service value(124.00×10⁴ RMB)and scientific research service value(71.52×10⁴ RMB)accounted for comparatively high proportions(3.58% and 2.07%,respectively); the rest,such as oxygen generation value(31.34×10⁴ RMB),climate regulation value(61.06×10⁴ RMB)and waste treatment value(14.60×10⁴ RMB)accounted for lower proportions of the ESV.However,for the year 2013,the total ESV of this area decreased to 814.10×10⁴ RMB,and the unit ESV decreased to 4.07×10⁴ RMB/hm².In the composition of the ESV,the aquaculture production service value(540.00×10⁴ RMB)was much lower than that of the former year,but it still accounted for the largest proportion(66.33%)of the ESV; the oxygen production service value(31.34×10⁴ RMB),recreation service value(124.00×10⁴ RMB)and scientific research service value(71.52×10⁴ RMB)were consistent with the previous year,however,their proportions increased to 3.85%,15.23% and 8.79% of the ESV,respectively; the regulating service(including climate regulation and waste treatment)value decreased sharply during this year,however,it accounted for comparatively higher proportion of the ESV than that of 2012.We concluded that the degradation in the ESV was due to decrease of aquaculture production service,which was mainly caused by high stocking intensity and environmental degradation.In conclusion,the oyster culture promotes the ESV of the Dapeng Cove,however,reasonable regulation should be made for the sustainable development of the ecosystem function of this cove.