As the demand for humus (HS) in agriculture increases annually, most of the HS is extracted from coal and other energy sources. In order to reduce the dependence on non-renewable resources such as fossil energy, there is an urgent need to explore more avenues for artificially synthesized HS. This study used different proportions of potassium hydroxide and potassium persulfate to activate sulfate free radicals (SO4−•) depolymerize and oxygenate alkaline lignin, and form humus-like (HS-like) conditioners. Through characterization of the total organic carbon analysis instrument, it was found that compared with untreated lignin, the HS-like content of the experimental groups with 0.05, 0.25, and 0.50 g of KOH increased by 2.38%, 8.58%, and 1.49%, respectively. The content of humic acid in the experimental groups supplemented with 0.05, 0.25, and 0.50 g KOH was 77.79%, 81.42%, and 81.42% higher than that of fulvic acid, respectively. The resulting humic acid content was much higher than that of fulvic acid. Fourier transform ion cyclotron resonance mass spectrometry revealed that lignin components tended to have a regional transformation of higher O/C or higher H/C. The results of seed germination and salt tolerance determination of pakchoi (Brassica chinensis L.) showed that HS-like substances formed play the role of auxin. These findings suggest that the utilization of alkali-activated persulfate for depolymerization and oxidation of lignin holds promise in addressing the demand for HS, thereby offering a viable strategy to enhance the value of lignin.