Persulfate (PS) oxidative degradation of phenol in an aqueous solution was studied in the presence of sorghum-straw biochar (S-BC). The effects of critical parameters, including sodium persulfate (PS) concentration, dose of catalyst, and the initial pH, were investigated. The results show that the ratio of phenol degradation in S-BC/PS system is obviously better than those of single S-BC and PS. The maximum removal efficiency of phenol reached 99.7% with PS/phenol molar ratio of 50:1, S-BC dosage of 1.5g/L, initial pH of 11and reaction time of 15h. Radical mechanism was studied and two radical scavengers (methanol (MA), tert-butanol (TBA)) were used to determine the kind of major active species taking part in the degradation of phenol. Finally, the recovery performance of S-BC was studied through the S-BC reuse experiments. In summary, the method of activating PS with S-BC may offer great benefits in remediation of phenol-contaminated water.