Epipelic algal community and phytoplankton community are two correlative communities in the same ecosystem of West Lake, Hangzhou. In the 1940s, Aphanothece stagnina was a dominate species in the epipelic algal community, occupying 98% -99% of the sediment in West Lake. Therefore forwarded a half centenary, following the eutrophication of the lake, the transparency of water decreased, and the decrement induced a corresponding succession of the epipelic algal community. The dominant species are changed from Aphanothece stagnina to Synedra herolinensis.The epipelic algal community in West Lake can be divided into 3 assemblages：(1) Synedra berolinensis Assem.： Distributed in Waixihu and Beilihu area with relatively high algal density, 302×104-575×10⁴ind·g^-1. Synedra berolinesis is a dominant species, occupying 41.2%-52. 8% of total algal number in the assemblages.(2)Fragilaria construens var venter-Syneclra berolinensis Assem.： Distributed in 3 lake areas which are located in the western part of the lake(Xilihu, Yuehu and Xiaonanhu). The algal density is 1/3 -1/8 of the first assemblage.(3) Aphanothece stagnian Assem.： Only exists in the inner lake on Santanyinyue island.