The taxonomic status of actinomycete strain JXJ 0170 was determined on the bases of morphological characteristics and 16S rRNA gene sequences.The fermentation time,physicochemical characteristics,alga-lysing efficiency and mode of the active components produced by strain JXJ 0170 were investigated by employing the lysis zones,chlorophyll-a contents,algae cell densities,morphology and photosynthetic intensity as indexs.And the acute toxicity of strain JXJ 0170 on aquatic animals was also studied by using Carassius auratus var. pengzesis and vivipara as bioindicators.The results showed that strain JXJ 0170 was a member of the genus Streptomyces.Its fermentation supernatant exhibited the highest alga-lysing activity after six days′ culture,and the alga-lysing efficiency was over 91% after Microcystis aeruginosa being treated with 2% fermentation supernatant for 3 days.The alga-lysing components were mainly water-soluble substances,and relatively stability to the treatments of temperature and pH,and perforated the algae cells and inhibited the photosynthesis of algae cells.Spores of JXJ 0170 could germinate on algae lawn and form lysis zone;and its mycelia also exhibited strong alga-lysing activity with dose effect.These results indicated that strain JXJ 0170 could lyse algae cells directly besides secreting active component to lyse algae cells indirectly.The culture broth of strain JXJ 0170 showed no obvious acute toxicity to C. auratus var. pengzesis and vivipara,and its control efficiencies in the field were 75.80%~93.80%.Actinomycete strain JXJ 0170 exhibited potential application in controlling cyanobacterial bloom.