The invention discloses a method for quickly starting reflux of powdered activated carbon. A mixing tank, a flocculation tank, a sedimentation tank and a degradation tank which are sequentially connected are contained. The method comprises the following concrete steps: firstly, determining optimal dosage of a coagulant under raw water conditions and the conventional coagulation technique by utilizing a coagulation stirring test, and determining the required carbon addition amount, reflux ratio and retention time; secondly, under the dosage of the coagulant, feeding water according to the predetermined retention time, adding the coagulant into the mixing tank, then discharging water by virtue of the flocculation tank and the sedimentation tank, and determining daily average mud yield; thirdly, adding the powdered activated carbon into the mixing tank, recording the moment as a first day; and fourthly, starting to uniformly reflux carbon mud in the degradation tank to the mixing tank according to the predetermined reflux ratio. The method disclosed by the invention has the advantages that activated carbon adsorption and a sludge reflux technology are combined, rate of removing ammonia nitrogen and organic matters can be greatly increased, and starting time of a powdered activated carbon reflux technology is effectively shortened.