This study is based on synchronous data collection in the intertidal zone of the raft culture area on Shengsi Gouqi Island from February to July 2022 （the rapid growth period of large seaweed from March to April, the mature period in May, and the decline period from June to July）. Relative importance index, Shannon-Weaver diversity, and Margalef richness index were used in combination with multivariate statistical methods such as clustering and sorting to analyze the species composition, abundance density changes, and clustering characteristics of amphipods attached to different structures on rafts and large seaweed.A total of 24 amphipod species were collected, belonging to 16 genera in 7 families within 2 suborders. Among these, 24 amphipod species were collected in the aquaculture habitat, while only 4 species were collected in the intertidal zone. The dominant species on the aquaculture rafts were Ampithoevalida, Sunampithoeplumosa, Hyaleschmidti, Caprellakroyeri, Caprelladecipiens, and Caprellaequilibra. In the intertidal zone, no dominant species were observed, and the IRI values for all species were less than 5.The overall abundance density of amphipods showed a monthly increasing trend, rising from （580±90）ind./m² during the rapid growth period of large seaweed from February to April to （3 800±400）ind./m² during the decline period from June and July. The highest average abundance density among different sites was found on the floaters, with （9 700±400）ind./m² while the lowest was observed on the mussel strings with （4 800±100） ind./m². Amphipods had the highest abundance and diversity during the rapid growth period of large seaweed, followed by the mature period, and the lowest values were observed during the decline period. Yibei strings had the highest abundance and diversity indices.In terms of clustering characteristics, amphipod communities not only exhibited significant temporal variations but also significant differences among different sites （P<0.01）. In terms of amphipods' selection and utilization of different large seaweeds, six amphipod species, including Ampithoe valida, exhibited a significant positive correlation with the biomass of brown and green algae （P<0.01）.The study found that large-scale raft-based aquaculture areas support a diverse, structurally varied, and highly abundant amphipod resource. This conclusion can provide an important basis for the construction of artificial habitats in marine ranching and the optimization of ecosystem structure.