Abstract: Three strains of bacteria which produce flocculating substances were isolated from activated sludge and soil.Every two strains of the bacteria among the 3 strains obtained above were selected to mix ferment by orthogonal experiment.The results showed that the combination of two strains called LH possessed the best flocculating activity.Identified on the base of 16SrRNA gene sequence,the two strains were pertained to Micrococcus sp.and Paenibacillus velaei.Though the preliminary study of the MBF-LH,it had been confirmed that MBF-LH is a kind of extracellular biopolymer and has a good thermostabilization.The best carbon source,optimal cultural temperature,initial pH value and rate of rotary shaker were saccharose,30℃,pH 8 and 120 r/min.Addition of KCl,CaSO₄ and K₂HPO₄ to the culture medium could obviously increase the flocculating rate.When applied to the wastewater treatment,MBF-LH had some good properties such as low dosage and high efficiency.