In this study, a novel type of α-Fe₂O₃ core microspheres were prepared hydrothermally by using FeCl₃, urea, and ascorbic acid, polyvinylpyrrolidone and nano-carbon powder as precursors. The microspheres were characterized by transmission electron microscope (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and BET/BJH methods. The results revealed that the core microsphere was self-assembled with the 40nm sized rice-grain shaped α-Fe₂O₃, the size of microsphere was uniform and the diameter was~50μm, the specific surface area of BET was between 25.45~32.46m²/g. This microsphere could activate peroxymonosulfate (PMS) to produce strong oxidative radical under ultraviolet (UV, mercury lamp) irradiation, which was confirmed as sulfate radical (SO₄^-·) with ESR (electron spin resonance) method. 98.6% of AO7 could be removed in 40 min in this system. It was found that PMS could effectively inhibit the recombination of photogenerated electrons (e_CB^-) and valence holes (h_VB⁺) as an electron capture agent, and AO7 can be oxidized by h_VB⁺, SO₄^-·and hydroxyl radical (OH·). After 10 cycles of application of α-Fe₂O₃, 80% of AO7 could be still removed in system. The effects of different dosage of α-Fe₂O₃, PMS, initial pH and initial concentration of AO7 on the degradation rate of AO7 were investigated. The results suggested that 99% of AO7 was eliminated within 40min under the optimum conditions:the initial pH was 7.0, the concentration of α-Fe₂O₃ and the PMS were 1.0g/L and 0.3g/L, respectively. The study of anion effect indicated that CO₃^2-, NO₃^- and Cl^- could promote AO7 degradation, which needed a further investigation in future works.