The present invention provides a method for preparing a hollow octahedral cuprous oxide, which includes the following steps: (1) mixing a copper chloride solution and a sodium hydroxide solution, and then performing a precipitation reaction to obtain a precipitation solution; and (2) mixing the precipitation solution with glucose and ammonium hydroxide, and then reacting to generate the hollow octahedral cuprous oxide. In the present invention, firstly sodium hydroxide and copper chloride are reacted to generate a copper hydroxide precipitate; then glucose is used to reduce copper ions, and ammonium hydroxide is used to produce graded diffusion dissolution action on octahedral particles, such that the octahedral particles are gradually dissolved into hollow structures. It can be seen from the results of the examples that, the method provided by the present invention can prepare hollow octahedral cuprous oxide with an uniform and pure structure.