The invention discloses a method for preparing a foaming material of polyurethane by utilizing radiation. In the method, a Gamma radial generated by a radiomaterial or/and an electron beam generated by an electron accelcrator are used for carrying out radiation on the materials in a normal method for preparing the foaming material of polyurethane; then the materials after radiation are frothed according to the normal method for obtaining the foaming material of polyurethane, wherein, the accumulated amount of a radiation agent is 1 to 150kGy; the radiation time is once or more than once; and the used radiomaterial is <60>Co. The method can prepare the polyurethane foam with different mechanical properties under the conditions that the materials and the prescription are not changed and hasthe advantages of simple technique, convenient operation and being easy to realize industrialization. Based on a structure formed on the original chemical reaction, crosslinked points of radiation are formed between the molecular chains of each soft segment of the polyurethane foam to form a crosslinked netty structure. The method has high application value on the production field of the foaming material of polyurethane.