The capacity of a pulp and paper plant in China is 25,000m3/d. The system contains long-chain organics which is non-degradable. The concentration of effluent COD is often on the edge of the discharge standard. In order to increase the decomposition ability of the biological system and increase the load of COD in the biological systems. The plant added Novozymes BioRemove 1650 and Novozymes BioRemove 1150 to cultivate dominant bacteria which degrade COD rapidly. Through Bioaugmentation and long keeping dosing, the impact resistance of biological system has improved. The load of COD can be increased by 34.1% with stable decomposition. The removal rate of COD increased from 74% to 80%. The effluent water quality can be stable below the standard of effluent water.