The invention relates to a bipyridine bisphenol-aluminum catalyst for preparing unsaturated polyester and a preparation method; the bipyridine bisphenol-aluminum complex has a structural formula such as I; the X group is Cl, CH 3 COO, CF 3 COO or NO 3 , R 1 , R 2 , R 3 and R 4 The groups are simultaneously or independently H, a halogen atom, an alkoxy group, an alkane group or a substituted alkane group; an aromatic hydrocarbon group or a substituted aromatic hydrocarbon group. Prepared by reaction of 2,4‑disubstituted phenols with R 1 , R 2 , R 3 and R 4 The bipyridine bisphenol ligand; then dissolved in a good solvent, and added to the good solvent of the metal aluminum source, and reacted to obtain a catalyst, X-ray single crystal diffraction showed that the complex distorted the structure of the square pyramid. The synthesized catalyst was used to prepare unsaturated polyester. The obtained unsaturated polyester has a polyester segment content greater than 99%, and can be used for further copolymerization with vinyl monomers to prepare unsaturated polyester resins.