Introduction and stabilization of oxygen vacancies on hematite is an effective strategy for boosting photo-Fenton performance. Herein, a novel hydrothermal carbonization process was utilized to induce oxygen vacancies on hematite to obtain amorphous carbon encapsulated core-shell composite (Fe2O3-x@AC), using ascorbic acid as reducing agent and carbon source. Amorphous carbon was coated on hematite by Fe-O-C bond with a mass fraction of 10.2 wt%. Compared with commercial hematite, the signal appeared at g=2.003 in EPR spectrum of Fe2O3-x@AC composite, confirming the formation of oxygen vacancies (Vo). Thanks to the introduction of AC and Vo, Fe2O3-x@AC composite showed excellent photo-Fenton activities, and its photo-Fenton degradation rate for RhB and phenol were increased to 7 and 70 times of commercial hematite. •OH generated from heterogeneous photo-Fenton reaction of Fe2O3-x@AC catalyst is the dominant reactive radical for organic pollutants degradation. The improvement of photo-Fenton properties of Fe2O3-x@AC is mainly attributed to the synergistic effect of AC and Vo, in which the decomposition of H2O2 to produce •OH was promoted to enhance the oxidation ability, and the charge transfer ability and carrier density were increased to accelerate the reaction. This work will give new light for the defect engineering of photo-Fenton catalysts with improved reactivity.