The invention discloses a wood-based panel prepared from paper mill sludge and a method for preparing the same. The material of the wood-based panel comprises paper mill sludge and phenol formaldehyde resin adhesive, includes the following steps: 1) sludge drying; 2) sludge milling; 3) secondary drying; 4) sizing; 5) pavement; 6) thermopress adhesion; 7)product performance test after cooling. A deodorization method is also disclosed comprising the step of placing the active carbon and the wood-based panel in a sealed container for three weeks. The method of the invention adopts paper mill sludge as main material for preparing the wood-based panel, which has advantages of simple production and low cost. The preparation method not only enables the paper mill sludge from the paper mill getting efficient treatment, but also has a positive role for environmental pollution treatment.