The community stability is essential to better understand the community structure and ecosystem functioning, and the robustness can elucidate the degree of community stability. Using the fish data of bottom trawl samplings from 2015 to 2018 in the Pearl River Estuary, we established the annual ecological "snapshots" of networks based on the feeding relationship between the fish species. Four characters of the four annual networks were summarized as follows: ① all the networks belonged to the complex networks as the values of P(k) fitted the power-law distribution, indicating the high resistance of the networks to random disturbances (such as fishing and environmental change). The resistance was also a sign for the drastic environmental variations of estuaries habitat; ② the species richness varied significantly in 2015 and 2018, and the densities of networks(D)ranged between 0.03 and 0.10 and had been descending annually since 2015, indicating the degrading of network robustness regardless of species richness; ③ the networks were characterized by the common random networks, such as low average path length (all APL was 1) and low clustering coefficient (C ranged between 0.01 and 0.06), indicating that the networks had the high rates of energy flow and comparatively even distribution of fish species relations. This paper provided clues for the quantitative research on fish community structure and stability in the key habitats of the coastal waters.