The invention discloses a magnetic loaded catalyst of metallic ion-polyamide which is a composition of metallic ions and the polyamide treeing compound on the surfaces of Nano magnetic particles, the mol ratio of nitrogen-atoms and metallic ions in the polyamide treeing compound is 0.5 to 300, and the metallic ions are a cupric ion or manganese ions. The invention combines the characteristics that metallic ion-polyamide treeing compound complex catalyst has high catalytic efficiency and the Nano magnetic particles are easy to be recovered through a magnetic field, can enable PPO to obtain high yield when being applied to aqueous medium for preparing the PPO with only a little quantity, and can be recycled for reusage by the magnetic field after the oxypolymerization, thereby solving the problem that prior catalyst for preparing polyphenylether in the water medium has low catalytic efficiency and is difficult to recover.