Abstract: The soybean oil polyols were prepared by used epoxy soybean oil as raw material and used methanol as open loop reagent. The soybean oil polyols which hydroxyl value in the range of 80-170 mgKOH/g were obtained through controlling the reaction time. The best formula was obtained through exploring. Then, take the soybean oil alcohol replace the traditional polyether polyol partly and added to the formula. After foaming time, flexible PU foams were obtained. The products were taking various mechanical analysis and the results show that the mechanical properties of flexible PU foams are reach national standard requirements. The tensile strength can reach 0.13MPa above and the elongation at break can reach 150% above.