Abstract: ObjectiveStructure and diversity of fish community in Sousa chinensis nature reserve of Pearl River Es-tuary waters were studied to provide basic reference for the protection of S. chinensis and biodiversity in this area.MethodTrawl surveys were conducted in the waters of nature reserve in September,2015(autumn)and March,2016 (spring). By using the biomass and abundance method,the composition of fishery catches was counted and analyzed to measure the ecological characteristics index of fish resource in the survey area. Besides,the disturbance status of fish com-munity was assessed by abundance biomass comparison curve method.ResultTotally,fifty-seven fish species were caught in two cruises survey,which belonged to 51 genera,37 families,and 13 orders. In September,2015(autumn), the average biomass and abundance of fish was 1.63 g/m2 and 177.9 × 10-3 ind/m2 respectively,with the average biomass and abundance being 0.43 g/m2 and 25.2 × 10-3 ind/m2 respectively in March,2016(spring). Collichthys lucidus,Coilia mystus,Polynemus sextarius and Leiognathus brevirostris were dominant species of both seasons. In autumn,all of theecological characteristics indexes,including the Shannon-Weiner diversity index(H'),Pielou evenness index(J'),and Margalef abundance index(D),were higher than those in spring. In September,2015(autumn),the dominance curve of biomass dominance in the fish community of S. chinensis nature reserve of Pearl River Estuary waters was below the abun-dance curve. W was a negative value(-0.068),indicating that the fish community was under severe disturbance. On the contrary,in March,2016(spring),the location of the biomass dominance curve was above the abundance curve. W was 0.056,showing that fish community was not disturbed.ConclusionThe storage of fish resources in S. chinensis conser-vation area of Pearl River Estuary waters is low,which indicates a declining trend of fishery resources during these years. The fish community structure is comparatively stable in spring,but is distinctively affected by external disturbance in au-tumn. Water in the S. chinensis nature reserve in the Pearl River Estuary has been under mild contamination. Though it is still suitable for fish growth and development,real-time measures should be taken to monitor and protect the water and ecological condition in the future.