Abstract: Based on monthly fishery resources investigation data of demersal trawl from 1986~1987 in the Pearl River Estuary and adjacent waters，the paper quantitatively analyzed variation of fish community of various species by cluster analysis and principal coordinates analysis of a package of MVSP. The result described seasonal and spafial variations and showed that the waters can be divided into four seasons in temporal and five waters types in spatial，and compared with the traditional divided idea,and the rationality of the result was discussed. In addition，eight species of Caranx kalla，Pampus argenteus，Collichthys lucidus，Coilia mystus，Thrissa dussumieri，Trichiurus japonicus，Leiognathus bindus，Thrissa kammalensis were defined to be dominant species of fishes in the Pearl River Estuary by comsidering factors of individual,weight and frequeucy，and the seasonal and spatial variations of the dominant species were analyzed. 