Abstract: Three strains of Anabaena EH-A,EH-B and EH-C were isolated from Lake Erhai during Anabaena blooms occurred respectively in 2004,2005 and 2006 year.Taxonomic evaluation of the three strains were investigated based on morphology and 16S rRNA gene sequences in the study.Morphological features were described by the traditional morphological criteria:morphology of filament;presence or absence of gas ve-sicles;location of heterocytes and akinetes;shape of vegetative cells,heterocytes,akinetes and terminal cells;length and width of vegetative cells,heterocytes and akinetes.Based on these morphological characteristics,the three strains were classified as A.circicular & A.crassa group.The phylogenetic tree inferred from sequence analysis of the 16S rRNA gene showed that strains EH-A,EH-B and EH-C displayed 100% sequence homology.Another,the three strains closely clustered a group with some strains of A.circicular & A.crassa group and also exhibited 100% sequence similarity.Therefore,it was suggested that the three strains EH-A,EH-B and EH-C were all the members of A.circicular & A.crassa group.