The utility model discloses a mixing system of denitration catalyst, including many mixing rolls, dust remover and scrubbing towers, the air outlet valve of many mixing rolls passes through pipeline UNICOM after the dust remover is continuous with the air inlet of scrubbing tower, the lower floor of scrubbing tower is equipped with the reservoir, and the top of scrubbing tower is equipped with back the elephant trunk, and the top of the inherent air inlet of scrubbing tower upwards is provided with spraying district, spray zone and water droplet district in proper order, the reservoir links to each other through the aqueous ammonia feed liquor valve of first water pump with the mixing roll, the advantage lies in having addd dust remover and scrubbing tower in order constituting mixing system on current basis, the V2O5's that avoids through the effect of dust remover outer row, and messenger's production safety is gone on, avoids the pollution to the environment, make the auxiliary material such as ammonia in waste gas can absorbate through the district that sprays, spray zone and water droplet district in the scrubbing tower, aqueous ammonia feed liquor valve that scrubbing tower lower floor reservoir passes through water pump and the mixing roll back that links to each other have formed the recycle of wastes material.