Abacterial strain A25, isolated from activated sludge and identified as Bacillius megaterium, could produce flocculant, The optimum carbon and nitrogen sources are maltose and yeast extract, respectively. The optimum pH range is 7.0～10.0. The flocculant was synthesized during the cell growth. The flocculant mainly exists in the supermatant. The partial purified flocculant could be kept in 60C for 1 hour without losing activity.