From Nov. 2003 to Aug. 2004, macrobenthic assemblages were investigated seasonally at the east tidal flat of Lingkun Island, Wenzhou Bay. A total of 33 taxa, including 21 families, 8 classes and 7 phyla, were found. Most of them were mollusks, crustaceans and polychaetes. The species numbers found at three tidal flat (high, middle and low) were 25, 30 and 14. The average value of Margalef′s and Shannon-Wiener′s indices were the highest at high tidal flat (2.26 and 2.04), following by middle (2.04 and 2.10) and low (1.02 and 1.50) tidal flat. The average values of Pielou′s and Simpson′s dominance indices had the opposite trend: high (0.89 and 0.14) < middle (0.85 and 0.16) < low (0.96 and 0.25) tidal flat. The species belonged to five different trophic functional groups: Phytophagous (12), Camivorous (8), Omnivorous (7), Planktophagous (3) and Detritivorous (2) in qualitative samplings. Then 3, 8, 5, 3 and 2 kinds of species belonged to Planktophagous group, Phytophagous group, Camivorous group, Omnivorous group and Detritivorous group respectively in quantitative sampling. The density and species number of each functional group did not display seasonal variation by the two-way ANOVA method. Without regarding the seasonal variation, density of the Phytophagous group (54.00±1.41, 32.00±6.32 and 0 respectively to high, middle and low tidal flat) and Camivorous group (54.00±4.76, 64.50±4.65 and 22.00±3.37 respectively to high, middle and low tidal flat) had distinct difference among the different zones of tidal flat, the species number of the Phytophagous group (5.25±0.25, 3.75±0.48 and 0 respectively to high, middle and low tidal flat) and Omnivorous group (1.25±0.48, 1.75±0.25 and 0.25±0.25 respectively to high, middle and low tidal flat) had distinct difference among the different zones of tidal flat. The results show that there was variation of functional groups among habitats. The Planktophagous group, Phytophagous group and Camivorous group were the primary components of the macrobenthic community at high tidal flat, the Planktophagous group and Camivorous group are the primary components of the macrobenthic community at middle tidal flat, then the Camivorous group was the primary component of the macrobenthic community at low tidal flat. The change of components of macrobenthic community reflected the change of food source in different zones of tidal flat. Because the plants decreased in the gradient from high, middle to low tidal flat, the Phytophagous group decreased along the direction of high, middle and low tidal flat. There was no Phytophagous group at low tidal flat. The density and species number of the Detritivorous group was similar in the three zones of the tidal flat. In conclusion, there were 5 functional groups in the macrobenthic community including the Planktophagous group, Phytophagous group, Detritivorous group, the Omnivorous group, and the Camivorous group; there were 4 nutrition levels at the macrobenthic community with the food resource, then the macrobenthos were the second, third and fourth level in the system, the first level included the dross, plankton and plant, the second level included the Planktophagous group, Phytophagous group and Detritivorous group, the third level was the Omnivorous group, the fourth level was the Camivorous group; which implies the tidal flat with a complicated food web.