A preparation method and application of titanium-cobalt spinel belongs to preparation methods and applications of transition-metal spinel, and specifically is a preparation method for a titanium-cobalt spinel (Co2TiO4) octahedral-nanostructure material and an application of the titanium-cobalt spinel (Co2TiO4) octahedral-nanostructure material to a negative electrode material of a lithium ion battery. A mild liquid phase synthesis technique is utilized to prepare a cobalt titanate nanostructure, and parameters in a reaction process are adjusted and controlled, so that the titanium-cobalt spinel octahedral-nanostructure material is compounded conveniently in low cost and is applied as the negative electrode material of the lithium ion battery. The preparation method comprises the steps of: respectively preparing solutions by utilizing a titanium source and a cobalt source, mixing the prepared solutions according to a molar ratio of (1-5) : 1, stirring the mixed solution uniformly, and putting the uniformly stirred solution in a closed pressure-resistant vessel to react for 8-40 hours at 100-250 DEG C, wherein an alkali additive is added to the titanium-source preparation solution, and a saccharide additive and an amine additive are added to the cobalt-source preparation solution. According to the preparation method, the raw materials are easy to obtain, a synthesis method is simple, and the controllability of operation steps is high; the obtained titanium-cobalt spinel has high purity and uniform particle size, and expanded production is easy. If the titanium-cobalt spinel octahedral-nanostructure material is taken as the negative electrode material of the lithium ion battery, the electrochemical performance is excellent.