A　total　of　348　species　belonging　to　8　phyla　and　125　genera　were　observed　in　seasonally　sampled　phytoplankton　of　tidal　rivers　from　13　sampling　sites　around　Luoyuan　Bay,　and　all　field　samplings　were　carried　out　in　productive　period　(March/June/August/　December)　at　ebb　tide.　Bacillariophyta　species　were　the　most　abundant　species,　followed　by　Chlorophyta,　Cyanophytes,　Euglenophyta,　Cryptophyta,　Dinophyta,　Xanthophyta　and　Chrysophytas.　Seasonal　distribution　index　(SDI)　value　ranged　from　0.63　to　0.86,　which　meant　that　species　found　at　those　sites　in　4　seasons　tended　to　be　largely　different.　Phytoplankton　individuals　ranged　from　5.939×104　ind　L−1　in　winter　to　75.31×104　ind　L−1　in　autumn.　Phytoplankton　biomass　ranged　from　0.620　mg　L−1　in　summer　to　2.373　mg　L−1　in　autumn.　The　grey　correlation　analysis　(GCA)　showed　that　the　nutrient　variables　played　an　important　role　in　the　influence　on　phytoplankton　community　in　every　season.　The　canonical　correspondence　analysis　(CCA)　revealed　impact　of　environmental　variables　on　the　different　species,　most　of　Bacillariophyta　species　were　negative　correlation　with　nutrients　(TP　and　NH3-N)　in　the　four　seasons,　Chlorophyta　species　and　Cyanophyta　species　did　not　show　obvious　correlation　with　environment　variables　in　every　season.　The　combination　of　GRA　analysis　and　CCA　analysis　provided　a　method　to　quantitatively　reveal　the　correlation　between　phytoplankton　community　and　environmental　variables　in　water　body　of　tidal　rivers　at　this　region.　©　2017,　Science　Press,　Ocean　University　of　China　and　Springer-Verlag　GmbH　Germany.