Based on monthly investigation data of beam trawl and hang trawl in the Pearl River estuarine waters in 1998, the paper analysed species composition, bio logical characteristics and seasonal variat ion of f ishes by principal components, regression, and hierarchical cluster analysises. The results indicated that fishes in the waters consisted of coastal or estuarine small species, among them, Collichthys lucidus, Johnius belengeri , Pampus argenteus, Trypauchen vagina, Odontamblyopus rubicundus , Oxyurichthys tentacularis , Chaeturichthys stigmatias, Parachaeturichthys polynema, Ambassis gymnocephalus , Cynoglossus bilineatus, Cynoglossus semilaevis, Coilia mystus, Umbrina russelli , Caranx kalla, Osteomugil ophuyseni , Harpodon nehereus , Trichiurus haumela, Trichiurus brevis , Euplerogrammus muticus , Ilisha elongata, Setipinna taty , Engraulis j aponicus, Stolephorus commersoni , Thrissa vitirostris , Gastrophysus spadiceus, Fugu xanthopterus , Loligo beka and Loligo duvaucelii are principal parts of f ishery resources. Seasonal variation in species composit ion was obvious, and benthic group differed f rom pelagic group in the time of succession.