The invention discloses a method for preparing a cobalt oxide micro-sphere through a solution method. The method comprises the concrete steps of dissolving cobalt acetate tetrahydrate into a mixed liquid prepared from ethylene glycol and deionized water, transferring the solution into a high pressure reactor, putting the sealed reactor into a pre-heating drying box, gradually rising the temperature of the drying box to 200 DEG C to 210 DEG C according to the temperature rising speed of 2 to 5 DEG C/min, keeping warm at the temperature for 8 to 9 hours, cooling to room temperature after finishing reaction, and filtering, washing and drying the mixed liquid so as to obtain the cobalt oxide micro-sphere. The method for preparing the cobalt oxide micro-sphere through the solution method provided by the invention is simple in process, short in generation period, and low in cost, and meanwhile, the obtained product has high purity and a regular shape.