The invention relates to a method for catalyzing ozone to reinforce sludge dewatering by utilizing sludge-derived biochar. The method comprises the following steps: (1) preparing the sludge-derived biochar: performing high-temperature calcination and pyrolysis on sludge to obtain the sludge biochar, mixing the sludge biochar with Mn < 2 + > and Fe < 3 + > solutions, stirring, performing ultrasonic treatment, adding alkali liquor, performing thermal activation, standing, aging, washing and performing vacuum drying, and obtaining the sludge-derived biochar loaded with the iron-manganese spinel; and (2) sludge reinforced dehydration: adjusting the pH value of the sludge to be dehydrated to weak acidity, adding the sludge to a conditioning reaction device, adding the sludge-derived biochar, uniformly stirring, introducing ozone for treatment, and dehydrating to obtain the dehydrated sludge. According to the method, the sludge derived biochar with efficient catalytic performance is prepared from the sludge of the sewage plant, ozone treatment is coupled, the dewatering performance of the sludge can be effectively improved, the dosage of chemicals is reduced, secondary pollution is avoided, the subsequent transportation and treatment cost of the sludge is saved, and safe treatment of the sludge is facilitated.