The community dynamics and potential carbon fixation of intertidal macroalgae were investigated monthly from April 2014 to April 2015 in the northwest coast of Yellow Sea. Seasonal variations in biomass and carbon fixation were presented and showed close relationship with community structure. The carbon fixation rate ranged from 0.48±0.13 mg C/(g_FW·d) to 4.35±0.12 mg C/(g_FW·d). Sargassum thunbergii, Chondrus ocellatus and Ulva intestinalis were three most influential species which contributed 27%, 21.9% and 18.5% variation of carbon fixation rate, respectively. Standing carbon stocks ranged from 7.52 gC/m² to 41.31 gC/m², and estimated carbon stocks varied from 11.77 gC/m² to 96.49 gC/m². The larger difference between estimated and standing carbon stocks implied that more fixed carbon was exported from the community in summer and autumn than in winter. This study suggested that intertidal macroalgal community could provide a potential function in carbon fixation of coastal ecosystem.