The morphology,16S rDNA and phospholipid fatty acid composition of two isolates including CB001 and CB002 cultured in liquid medium and on the solid plate was studied.The result of morphology and phylogeny analysis confirmed that both CB001 and CB002 were belonged to Arthrospira platensis.The result of fatty acid composition analysis showed that 16∶00,16∶1 w7c,18∶1 w9c,18∶2 w6c,14∶0 anteiso and 16∶1 w7c alcohol were the main PLFAs in the genus Arthrospira.18∶1 w5c and 16∶3 w6c were the characteristic PLFA of strain CB001 and CB002,respectively.The PLFA patterns of both CB001 and CB002 were affected significantly by culture conditions.Further application of PLFA technique could be used to identify and classify Arthrospira,or estimate biomass or purity in large-scale bacterial proliferation.