The invention discloses a method for recovering highly pure manganese dioxide from waste manganese dry batteries, and a catalysis application of the highly pure manganese dioxide. The method concretely comprises the following steps: carrying out fragmenting sorting, vibration screening, water washing desalination, alcohol washing degreasing, alkali washing, pickling and neutral water washing on waste dry batteries, filtering out manganese dioxide-containing black powder, mixing the manganese dioxide powder with a strong oxidation additive or strong oxidant solution under closed conditions through using the catalysis activity of manganese dioxide, and carrying out low temperature oxygen-rich roasting to remove carbon and acetylene black in order to prepare the highly pure manganese dioxide which can be applied to catalytic degradation of petroleum chemical engineering phenol wastewater. The idea of treating wastes by using wastes is used to reasonably utilize solid wastes and separate and purify the active catalyst used for treating industrial wastewater. The method has the advantages of low energy consumption, greenness and environmental protection, simple process flow, realization of avoiding of pyrolysis of manganese dioxide through low temperature oxygen-rich roasting and conversion of low-valence alkali manganese salt, high purity and large output of the above product, high recovery rate, rapid catalytic degradation of the petroleum chemical engineering phenol wastewater, and high catalytic degradation efficiency, and allows the chemical oxygen demand (COD) of treated industrial wastewater to reach national industrial wastewater discharge standards.