Abstract: In order to study effect of Lactobacillus fermentation on the main functional components of of Spirulina platensis,Spirulina platensis was fermented by Lactobacillus plantarum,Lactobacillus casei,Lactobacillus lactis and Bacillus coagulans. The contents of total phenols and flavonoids in Spirulina platensis fermentation supernatant and ethanol extracts of fermented or unfermented Spirulina platensis powder were analyzed,and their antioxidant activities were also determined. The results indicated that the total phenol and total flavonoids content in the supernatant changed significantly after fermentation(P<0.05). The best effect on total phenol content increased by 39.8% fermented by Lactobacillus plantarum,and Lactobacillus casei the best for improving total flavonoids content increased by 41.3%. The total phenol,phycocyanin and carotenoids of the alcohol extract of fermented or unfermented Spirulina platensis powder,decreased by 22.5~30.1%,97.5~99.5%,and 86.9~94.5% individually. However,the DPPH· scavenging ability of fermented supernatant and alcohol extracts of fermented or unfermented Spirulina platensis powder increased by 5.6%~6.5% and 7.4~8.3% individually,indicated that fermentation process might produce new antioxidants. In addition,the main active components and antioxidant activities of the fermented supernatant or powder of different strains were significantly different,suggested that the species of lactobacillus had an important influence on the metabolites of Spirulina fermentation.