Hangzhou Bay, which is located in northeastern Zhejiang Province, is a typical subtropical estuary. Because of the bay's rich food resources, many fish, shrimp, and crab species migrate from deep sea waters to Hangzhou Bay for spawning and feeding. However, recent coastal pollution and overfishing have seriously damaged the bay's marine environment and fishery resources. Some commercial species, such as , have declined or disappeared, which may contribute to the collapse of the marine ecosystem. Macroinvertebrates are one of the most important groups of marine organisms in estuaries and play an important role in estuary food chains. Therefore, the current macroinvertebrate community structure and condition of the marine environment in Hangzhou Bay must be studied in order to provide scientific information for the ecological remediation efforts in Hangzhou Bay. The macroinvertebrate community structure of northern Hangzhou Bay was characterized, based on a field investigation of fishery resources in February, May, August, and November of 2016. The investigation focused on species composition, seasonal variation in macroinvertebrate community structure, and the relationship between the community and environmental factors. Macroinvertebrates were captured at 12 sampling stations using a beam trawl of 20 m in length and 4 m in width. The beam length was 6 m, and the opening height of the net was 2 m, with the smallest net mesh of 25 mm. Trawling was performed at 1.5-4.4 knots for 15-63 min at each station, and water temperature, salinity, and depth were recorded at the same time. Index of relative importance, cluster analysis, and multivariate statistics were used to analyze species composition, dominant species, and community structure characteristics. A total of 22 species (18 genera, 15 families, 5 orders, and 4 classes) were captured during the study. Decapoda dominated, accounting for 77.3% of the total species number, followed by Stenoglossa, which only accounted for 9.1%. Five dominant species were identified (Potamocorbula amurensis, and was a dominant species during all seasons, whereas was a dominant species during winter, spring, and autumn. CLUSTER analysis and non-metric multidimensional scaling (NMDS) indicated that the macroinvertebrate community of northern Hangzhou Bay could be clustered into two groups at 44% Bray-Curtis similarity level. Group I was classified as the winter/spring assemblage, whereas group Ⅱ was classified as the summer/autumn assemblage. Group I consisted of 19 stations in February and May, and Group Ⅱ consisted of 21 stations in August and November. The dissimilarity between Group I and Ⅱ was as high as 57.76%, and analysis of similarity (ANOSIM) indicated that community structure of the two groups was significantly different (<0.01). BIOENV indicated that the macroinvertebrate community structure of northern Hangzhou Bay was closely related to water temperature and salinity (correlation coefficient:0.39). The present research indicated that the macroinvertebrate community structure of northern Hangzhou Bay is simple and that the main dominant species were small shrimps. There was a significant difference in the seasonal variation of the macroinvertebrate community structure of northern Hangzhou Bay, and the dominant species varied each season. Water temperature, salinity, and the ecological migration of dominant species probably impact the replacement of macroinvertebrate community structure in northern Hangzhou Bay, and the macroinvertebrate community structure of northern Hangzhou Bay is seriously disturbed.