The invention discloses a method for preparing a beta-Ga2O3 nanosphere by adopting a chemical vapor deposition method. According to the method, a catalyst is not needed, the operation is simple, and the repeatability is good. The method comprises the following steps that gallium oxide powder with the purity higher than 99% and active carbon powder are fully mixed to prepare a reaction source material according to the mass ratio of 1 : 1-2, the reaction source material is put into a quartz boat, then the quartz boat is placed into a high-temperature heating region of a quartz tube of a chemicalvapor deposition system, and a silicon substrate is located at the position 1-2 cm right above the reaction source material; argon is introduced as carrier gas, wherein the flow of the argon is 30-90ml/min; when the heating temperature reaches 1120-1200 DEG C, oxygen is introduced, wherein the flow of the oxygen is 30-100 ml/min, and the growth time is 30 minutes; and the oxygen is cut off, theflow of the argon is kept, the temperature is cooled to room temperature, and then a sample is taken out.