The preparation method and application of highly active titanium catalysts belong to the field of polyester catalysts. The specific method is as follows: dissolve titanium metal alcoholate in an organic solvent, hydrolyze the titanium dioxide precipitate obtained, wash and filter, and then place the precipitate in a solution of organic modifier, or the organic modifier is directly added to the solution during the hydrolysis process. In organic solvents, organically modified titanium dioxide is obtained. Catalysts are used to prepare saturated polyester resins with relative molecular weights less than 10,000, or thermoplastic polyesters and polyester polyesters with relative molecular weights greater than 10,000. The present invention first proposes a new idea of ??using organic modifiers to organically modify high specific surface area titanium dioxide. The introduction of organic modifiers improves the quality of polyester. Titanium dioxide modified by organic modifiers not only has high activity, Moreover, it overcomes the problem of yellowing color of PET polyester obtained during the catalytic polymerization process of titanium dioxide precipitate.