The biomass size spectrum (BSS) theory was introduced by Sheldon et al. in 1972 to describe the features of marine pelagic ecosystems. Schwinghamer was the first to extend this concept to benthic assemblages. Traditionally, benthic communities are described by structural variables, such as abundance, species composition, and biodiversity indices. Analysis of the distribution of biomass by size is an ataxonomic approach to studying the structures and functions of the benthic communities. The introduction of the BSS theory provides a new method for benthic ecology research. Compared to taxonomic approaches for studying the structures and functions of benthic communities, the BSS theory is easier to operate, in which calculation errors caused by inaccurate taxonomic identification may be avoided. Because of the urgent need to understand the structures and functions of marine ecosystems, and to accurately detect the ecological systems, the fields of application for the BSS theory will become more extensive. In China, most studies on the size spectrum of zoobenthos have been conducted in the subtidal zone, with only a few studies having been conducted in the intertidal zone. In addition, no studies have been conducted in mangrove swamps. To provide a scientific basis for the ecological protection and sustainable use of the Gaoqiao Mangrove Wetlands, the BSS of the benthic fauna in this area was constructed from macrofaunal and meiofaunal samples collected in January, April, July, and October 2010. The main results showed that the BSS of the benthic fauna in Gaoqiao Mangrove Wetlands exhibits 3 peaks. The first peak appeared at a grain size of -2, and comprised nematodes. The second peak appeared at grain sizes of 4-12, and comprised oligochaetes, polychaetes, and small-bodied crustaceans. The third peak appeared at grain sizes of 13-22, and comprised large-bodied gastropods, bivalves, and crustaceans. For Aegiceras corniculatum, Sonneratia apetala and Bruguiera gymnorrhiza biotopes, there was a trough at grain sizes 0-4, which was the intersection grain size between macrofauna and meiofauna. The slope values of the normalized biomass size spectra (NBSS) were greater than -1, while the intercepts ranged from 16.533 to 18.150. The intercepts and the biomass of minimum size (BMS) for A. corniculatum and S. apetala biotopes were higher than those in B. gymnorrhiza and Sporobolus virginicus biotopes. This result indicated that zoobenthic productivity in the A. corniculatum, and S. apetala biotopes were higher than that in the B. gymnorrhiza and S. virginicus biotopes. The intercept and BMS in fall were higher than those in other seasons, indicating that zoobenthic productivity was higher in fall compared to the other seasons.