The invention relates to a method for preparing polyether-ketone by an ionic liquid supported acetyl acetone metal catalyst. The method of the invention comprises the following steps: carbon dioxide and alkenyl ether are taken as raw materials and an ionic liquid supported acetyl acetone metal coordination compound is taken as a catalyst to generate the polyether-ketone by copolymerization for 1-48 hours under the pressure of 0.1-5.5 MPa and the temperature of 25-130 DEG C. The catalyst used by the method of the invention has very good thermal stability, being stable to air and water, and easy operation as well as higher catalytic activity. The prepared polyether-ketone of the invention is characterized by higher molecular weight and good selectivity, etc.