The invention discloses a method of using normal pressure oxygen to oxidize aromatic alcohols to prepare aldehyde in presence of graphene supported nano copper powder (catalyst). Graphene supported nano copper powder is prepared by the following steps: carrying out in-situ reduction between graphene oxide and a copper salt solution, and then carrying out separation and drying to obtain the graphene supported nano copper powder. In water, normal pressure oxygen high selectively oxidizes aromatic alcohols into aryl aldehyde in the presence of the composite catalyst and an initiator, and the conversion rate is high. Reactions are carried out under a normal pressure, water is taken as the solvent, the method is environment-friendly, the conversion rate of aromatic alcohols is more than 96%, the aldehyde selectivity is more than 95%, and the catalytic performance is excellent for many aromatic alcohols.