In order to change the heating mode in microwave heating process, polyimide (PI)/carbonyl iron powder (CI) composite film was prepared and its properties were investigated. The properties of the composite film were analyzed by infrared spectroscopy, scanning electron microscopy, mechanical properties, oxygen permeability and moisture permeability and microwave heating. The results showed that the addition of carbonyl iron powder to polyimide was physically binding. When the content of carbonyl iron powder exceeds 25%, agglomeration begins to occur. It was found that the elastic modulus was the smallest when the content was 20%. When the content was 15%, the oxygen permeability and moisture permeability coefficient was the lowest. With the increase of carbonyl iron powder content, the rate of heating and cooling of the composite film under microwave heating increased. The conclusion is that PI/CI composite film can absorb microwave energy to heat energy, which is a new type of absorbing packaging material and provides a new idea for packaging material design in microwave heating process.