The present invention discloses a nucleophilic acyl substitution-based polymerization catalyzed by oxometalic complexes. In the first place, the first monomers with a plurality of carboxyl groups, and the second monomers with a plurality of protic nucleophilic groups are provided, wherein the protic nucleophilic groups comprise hydroxyl, amine, or thiol group. Next, catalyzed by the mentioned oxometallic complex, the first monomers and the second monomers are polymerized into the designed polymer. On the other hand, this invention discloses another nucleophilic acyl substitution-based polymerization catalyzed by oxometallic complexes. In the first place, monomers with at least one carboxyl (phosphonyl) group and at least one masked protic nucleophilic group are provided. Then, monomers are polymerized into the designed polymer, catalyzed by the mentioned oxometallic complexes.