The invention provides a biological iron-removing manganese-removing functional bacterium, which relates to a microorganism. The invention solves the problems that the present biological oxidation manganese removing engineering flora is established by natural selection, the biochemical capability is weak, the manganese removing effect is poor; the establishment of the water treatment removing manganese biologic filter pond needs a long time for cultivation, domestication and startup, and the restoring period after the engineering flora is damaged is long. The biological iron-removing manganese-removing functional bacterium MSB-4(Chryseobacterium sp.) belongs to flavobacterium, is preserved in the General Microorganism Center of China Commission of Culture Collection Management, the storage date is 30 Octomber 2007, the storage number is CGMCC No.2239; strain MSB-4 is aerobic strain, the length is 1.5-2 micrometers, the width is 0.8-1.1 micrometers, the strain is short rod-shaped cell with two blunt ends; brown yellow colony is formed on the substrate, the colony is non-transparent and round; the strain MSB-4 has metachromatic granules and lipoid granules, has no brood cell; N, N, N<1>, N<1>-tetramethyl-para-phenylene diamine stain is positive. The biological iron-removing manganese-removing functional bacterium MSB-4 of the invention has the capability for removing the Mn<2+>, <Fe2+> in the water, Mn<2+> removing rate can reach up to 94.44 percent, and the Fe<2+> removing rate can reach up to 90.13 percent.