Abstract: In order to assess the marine carrying capacity of Daya bay, this paper established a evaluation index system of marine resource and environment carrying capacity(MERCC) based on marine ecosystem services, which included four factors and 14 indexes.The results showed that the value of MRECC of Daya bay ranged from 0.23 to 0.72, and the average value was 0.51, with an increasing trend as a whole.The MRECC of Daya bay showed low level in 2000~2007, and then increased to middle level in following years.The MRECC was mainly influenced by economic factors, social factors and ecological factors.The key procedure to improve MRECC was to control the land sourced pollutant, to optimize the industrial structure and to restore the nature resource.