Abstract: Five strains(JR-1～5)are isolated from the sludge,each of which can decolor bromanine acid efficiently.JR-1 and the mixed bacteria group are chosen to study on decoloration conditions optimization and decoloration mechanism.The results showed that the decoloration ability of the mixed bacteria group is no better than that of the single strain;both the mixed bacteria group can endure bromanine acid to the concentration of 5 g/L;the optimum range of pH value is 5～7;the bromanine acid is degraded to form a new product with maximum absorption wavelength at 410 nm.