The invention discloses a pretreatment method of cobaltosic oxide. The method comprises the steps of mixing a titanium-containing organic matter with an organic solvent so as to obtain a mixed liquid; adding cobaltosic oxide powder into the mixed liquid under a stirring condition so as to form a turbid liquid, adding deionized water into the turbid liquid, adequately stirring the turbid liquid and the deionized water until a uniform pulp-shaped fluid material is formed, and drying the uniform pulp-shaped fluid material so as to obtain a cobaltosic oxide compound. The high-voltage lithium cobalt oxide can be obtained by adequately mixing the obtained cobaltosic oxide compound, a lithium source and a dopant to obtain a mixture, and performing solid sintering and covering on the mixture at a high temperature. The tap density of the prepared high-voltage lithium cobalt oxide is more than 3.0g / cm<3>, the compaction density is more than 4.2g / cm<3>, the primary discharge gram capacity in the range of 2.8V to 4.34V can reach more than 164mAh / g, and the circulating capacity retention rate in 300 weeks is more than 89 percent. The prepared high-voltage lithium cobalt oxide has the advantages of good processing performance, high tap density, good circulating performance, high specific capacity and the like.