A well-crystallized cryptomelane-like material (α-MnO2) has been synthesized by redox reaction between Mn2+ and MnO4- under acid condition at certain temperature. This composite material was characterized by X-ray diffraction, volumetric (N2 adsorption-desorption) and scanning electron microscopic analysis, as well as the Laser Raman spectroscopy. Synthetic cryptomelane was used in the oxidation of hydroxylation of phenol in order to study the oxidation activity. The result showed that the degradation rate of 50 mL of 100 mg/L phenol could recch to nearly 100%, under the conditions of pH 2.0, 3 g/L of synthetic cryptomelane with the grain size of 120~160 mesh, and the reaction time of 5 h at room temperature. The treated wastewater has achieved the industrial wastewater discharge standard. Moreover, the economic cost of synthetic cryptomelane was cheaper and the treatment effect of phenol becomed better. Therefore, the synthetic cryptomelane is believed to have a bright prospect in the development of industrial sewage treatment.