The invention discloses a preparation method of a graded spherical cuprous oxide hollow nano particle. The preparation method of the graded spherical cuprous oxide hollow nano particle is characterized by comprising the following steps of: (1) dissolving copper salt in water, (2) dropwise adding a mixed aqueous solution of hydrazine hydrate and acetate at 5-40 DEG C under a stirring condition, and (3) after dropwise adding, continuing stirring for 10-30min at 5-40 DEG C, centrifuging, washing with water, performing vacuum drying, and obtaining the graded spherical cuprous oxide hollow nano particle, wherein a molar concentration of Cu<2+> is 0.1-4mol / L, and a molar ratio of acetate (CH3COO<->) to hydrazine hydrate (N2H4) to copper salt (Cu<2+>) is (1-3):(0.5-4):1. According to the method, a reaction system is simple, raw materials are cheap and easy to obtain, and the method produces no hazardous waste, meets a green production concept, is simple in process route, easy and simple to operate, mild in reaction condition, short in reaction time and high in efficiency, and is suitable for mass production.