The invention relates to the field of organic synthesis, and discloses a bis-Schiff base rare earth complex as well as a preparation method and application thereof. The complex has a structure represented by a formula (1) in the description, wherein R1 is at least one group selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, isopropyl, primary butyl, sec-butyl, tert-butyl, methoxyl, ethoxyl, n-propoxy, isopropoxy, primary butoxy, sec-butoxy and tert-butoxy; and R2 is at least one group selected from the group consisting of hydrogen, methyl, ethyl, n-propyl, isopropyl and ahalogen. The bis-Schiff base rare earth complex provided by the invention has the function of catalyzing polymerization of polar monomers, and when the bis-Schiff base rare earth complex catalyzes polymerization of the polar monomers, the conversion rate is high, and the molecular weight of a polymer is large.