The invention relates to the technical field of phenylenediamine production and particularly discloses a post-processing method of a phenylenediamine hydrolysate. The post-processing method of the phenylenediamine hydrolysate is characterized by comprising the following steps: performing three-stage extraction on the hydrolysate, performing 3-8-stage extraction on each stage of extraction, filtering and impurity-removing an extracted oil phase and an extract aqueous phase in each stage, enabling the extracted oil phase rich in hydroquinone to enter a de-solventizing process and enabling the extract aqueous phase to enter a next stage for processing; then performing activated carbon adsorption and de-colorization treatment on the extract aqueous phase, filling activated carbon with a filling column and enabling the extract aqueous phase to continuously flow through the activated carbon filling column for absorption till the processed aqueous phase meets the use requirements for hydrolysis reaction with acid. The content of each of alcohol, acid, ketone, ether and ester in the processed aqueous phase is smaller than 50 ppm; after being mixed with pure water according to a certain proportion and blended with the acid, the aqueous phase has no effect on hydrolytic reaction of phenylenediamine even if repeated use; the processing is convenient, the principle is scientific, the utilization rate of reaction material liquid is improved, and greenness and economy are realized.