Catalyst for preparing polyoxyethylene, preparation method of catalyst and preparation method of polyoxyethylene

The invention relates to a catalyst for preparing polyoxyethylene, a preparation method of the catalyst and a preparation method of the polyoxyethylene. The catalyst comprises Lewis base, Lewis acid and a rare earth component, wherein the Lewis base is selected from bicyclic compounds with two or three N atoms on a ring, the Lewis acid is selected from trialkyl aluminum, and the rare earth component is selected from inorganic salts of rare earth elements; the molar ratio of the Lewis base to the Lewis acid to the rare earth component is 1: (0.5-4): (0.001-0.005). The Lewis base and the Lewis acid in the catalyst for preparing the polyoxyethylene have synergistic interaction, the synergistic catalysis effect of the Lewis base and the Lewis acid can be further improved in the presence of the rare earth component, the ethylene oxide ring-opening polymerization reaction can be carried out under mild conditions, and the prepared polyoxyethylene is a high-molecular-weight product and has the viscosity-average molec