The invention provides a deep treatment method of pulping and papermaking wastewater. The deep treatment method comprises the following steps: regulating the PH (Potential of Hydrogen) value of the biologically treated pulping and papermaking wastewater by using acid liquor; discharging the wastewater of which the PH value is regulated into a deep treatment work section, adding a poly ferric sulfate solution into a water inlet end of a pore plate reaction pool, carrying out oxidation reaction, quickly stirring, and controlling the PH of the wastewater; enabling the wastewater after the oxidation reaction is completed to enter a coagulation reaction pool, slowly mixing, controlling the PH of effluent, adding a polyacrylamide solution in the coagulation reaction pool, and carrying out flocculation reaction; enabling the wastewater after the flocculation reaction is completed to enter a final sedimentation pool for carrying out mud-water separation, adding alkali liquor in supernatant soas to regulate the PH, and forming standardized water. According to the deep treatment method provided by the invention, the treatment effect on the pulping and papermaking wastewater is good, the COD(Chemical Oxygen Demand) in the wastewater can be remarkably reduced, the effluent chromaticity can be effectively improved, and the removal rate of the COD is up to 80 percent of above; the expression of drug properties is increased, the sludge output is reduced, and the treatment cost is reduced.