Carrying capacity is critical for the sustainable development of fishery. Based on the data obtained from bimonthly surveys during the period from October 2008 to August 2009a trophic model of a mangrove planting-aquaculture coupling system was constructed by using the ECOPATH model with Ecosim software. Energy flows and ecological carrying capacityof the coupling system were analyzed and evaluated. The results showed that the constructed ECOPATH model consists of 14 functional groupswith the trophic level ranging from 1.00 to 3.05. The geometric mean of the trophic transfer efficiencies was 6.9%with 7.2% from detritus and 6.6% from primary producers within the system. The lower efficiencies were attributable to that most energy flows back to detritussuggesting that the food web was more dependent on detritus than on primary producers to support fishery. The ecosystem attributes statistics total primary production / total respirationtogether with low connectivity index ，（，we estimated the carrying capacity for tilapiaCtenopharyngodon idellusHypophthalmichthys molitrixwhich are the main cultured species in the system. The ECC was defined as the maximum biomass that a specified environment can support without significant change of major energy fluxes or structure of the food web. The ECC of tilapiasilver carp and bighead carp culture should be 5.82 t /hm²the effects of uncertainty of input parameters and sensitivity analysis of the ECOPATH were also explored.