Abstract: In Shanghai Tobacco Factory, a two-stage biochemical treatment system with 1920m³ (80m³/h) of daily treatment capacity had been used.However, the system was becoming not competent to deal with the wastewater of increasing pollution concentration, because that the sedimentation basin was not deep enough and the wastewater contained some undegradable fiber.The system was upgraded by way of:1) changing anaerobic basin into anoxybiotic basin;2) setting inclined plates in the sedimentation basin to compensate for basin depth;and 3) adding a filtrating device and applying sterilant after two-stage biochemical treatment.The treated water was of good quality close to the null emission required by environmental protection, and the medium water was reused more widely.