Abstract: A bacillus strain named A-9,which can produce bioflocculant with high flocculating activity,was screened from fertile soil.The test results of culture for A-9 show that the carbon sources nitrogen sources and initial pH of the cultural medium have important effects on the flocculating activity of MBFA9.MBFA9 can flocculate Gaoling suspension better than other bioflocculants without synergistic effects of Ca²⁺,Al³⁺ and other agents,and its dose is about 1/10～1/100 of other bioflocculants.The tests of treatment of river water with silt suspension,sulfur dyes wastewater and yellow wastewater from starch factory were carried out.It was found that MBFA9 has higher clearance of suspended solid and COD compared with polyacryamide.