Oscillatoria sp. is a so common and harmful cyanophytes in shrimp culture pond. In this experiment, sterilization filtrate of Brevibacillus laterosporus and Oscillatoria sp.were used to study algicidal effects in their different growth stages. Algae dry weight, chlorophyll-a and phycocyanin protein contents were measured in order to explore the best algae-lysing period and algicidal mechanism. The final aim is that providing theoretical basic for improving water envinment in shrimp pond. The results show that algicidal effects of sterilization filtrate to Oscillatoria sp. are very significant(P<0.01)when the algae-lysing bacteria in the stable and decline phases. After 7 days, algae dry weight were reduced by 51.77%、47.04% separately, chlorophyll-a content were decreased by 67.60% , 59.13% respectively, phycocyanin protein content were severally increased by 33.51%、30.97%. And similarly, the algicidal effect of sterilization filtrate of alage-lysing bacteria is so conspicuous(P<0.01)to the lag phase Oscillatoria sp.. 7 days later, algae dry weight were reduced by 63.90%, chlorophyll-a content were decreased by 69.72%, phycocyanin protein content were increased by 54.17%. The conclusion is that sterilization filtrate of Brevibacillus laterosporus in the stable phase has the best algicidal effect to the lag phase Oscillatoria sp..