A dimethoxy methane catalyst prepared through selective oxidation of methanol is a V2O5/TiO2 catalyst modified by an acidic compound containing chlorine, nitrogen or phosphorus, and is characterized in that components of the catalyst mainly include V and Ti, and modification components contain elements including chlorine, nitrogen or phosphorus. The method for preparing catalyst has the advantages of simple operation, good stability, and low and saved cost. When the method is applied to the preparation of dimethoxy methane by methanol one-step oxidation, the reaction temperature is greatly reduced, the conversion rate of methanol is 31.05%-60%, and the selectivity of dimethoxy methane is 86.04%-99%.