The invention discloses a method for catalyzing caprolactone polymerization by utilizing an aluminum complex containing a salicylaldehyde group. The method comprises the following steps: mixing a catalyst, an organic solvent, benzyl alcohol co-catalyst and caprolactone, carrying out ring opening polymerization reaction under the protection of anhydrous oxygen-free and inert gas, and then treatingthe reaction product to obtain polycaprolactone. According to the method disclosed by the invention, the self-developed aluminum complex containing the salicylaldehyde group is used as a catalyst to carry out the ring-opening polymerization reaction of caprolactone, the preparation method of the salicylaldehyde-containing aluminum complex catalyst is simple, the cost is low, the product yield is high, and the structure of the catalyst is diversified, the metal center aluminum coordinates with two-valent N,N,O,O of the ligand, the calytic activity is high, the stereoselectivity and the reactionrate are high, and the obtained polymer is a benzyloxy-terminated polymer, the molecular weight distribution is narrow, the molecular weight is controllable, the yield is high, and the market demandis met.