Seagrass beds provide essential ecosystem services, such as habitat for marine life, water quality purification, carbon sequestration, and climate regulation. For the Changshan Archipelago, which relies heavily on marine resources, the growth and development of seagrass beds are key factors affecting aquaculture. This study is based on data collected from a survey conducted in the nearshore waters of the Changshan Archipelago in August 2022, encompassing seagrass distribution and water sample data. The water samples were analyzed for various parameters, including salinity, suspended solids, pH, dissolved oxygen, sea temperature, nitrite-nitrogen, nitrate-nitrogen, and ammonia-nitrogen concentrations. A habitat suitability assessment of the seagrass beds in the Changshan Archipelago was conducted. The study calculated the suitability index for each environmental variable based on the abundance index, and then established a Habitat Suitability Index model using a weighted allocation method. The results indicate that the seagrass bed area in the study region is primarily composed of excellent and suitable habitats. The concentration of inorganic nutrients is a key factor influencing seagrass growth. The HSI model not only identifies the hierarchical distribution of habitats in seagrass areas, but also detects potential suitable habitats for seagrass. This provides scientific reference for future seagrass bed resource protection and artificial cultivation efforts.