The invention discloses a formula of flexible PU (polyurethane) foamed plastic. The formula is characterized by consisting of the following raw materials: 200 to 220 parts of polyether polyol, 0.5 to 0.7 part of tin catalyst, 0.3 to 0.4 part of amine catalyst, 102 to 104 parts of isocyanate, 20 to 25 parts of Freon-11, 8 to 8.5 parts of water and 2 to 2.5 parts of silicone oil surfactant, wherein the parts refer to parts by mass. The relevant properties of the flexible PU foamed plastic prepared by the formula are shown as follows: elongation is 165 to 170 percent, compression deformation is 7 to 7.3 percent, and tensile strength is 0.085 to 0.09MPa; the elongation of the flexible PU foamed plastic is effectively increased.