This paper presents some results on the nitrogen removal from domestic waste water by moving bed bio-film reactor (MBBR), where both nitrification and denitrification occurring simultaneously. Porous carrier was used to produce aerobic and anoxic zones locally in a single carrier pellet to perform nitrification and denitrification at the same time. Moving bed bio-film reactor is applied to enhance the mass transfer within the system. Compensating effect between nitrification and denitrification efficiency has been founded like the higher the efficiency of nitrification, the lower the efficiency of denitrification. When nitrification efficiency was reached more 90 percent, denitrification efficiency approached about 20 percent. Sizes of carrier and packing rates of cubic-shaped carriers were assessed for denitrification extent reached under oxic condition of medium.